Seattle Mariners Top 32 Prospects

Joe Nicholson-USA TODAY Sports

Below is an analysis of the prospects in the farm system of the Seattle Mariners. Scouting reports were compiled with information provided by industry sources as well as my own observations. This is the third year we’re delineating between two anticipated relief roles, the abbreviations for which you’ll see in the “position” column below: MIRP for multi-inning relief pitchers, and SIRP for single-inning relief pitchers. The ETAs listed generally correspond to the year a player has to be added to the 40-man roster to avoid being made eligible for the Rule 5 draft. Manual adjustments are made where they seem appropriate, but I use that as a rule of thumb.

A quick overview of what FV (Future Value) means can be found here. A much deeper overview can be found here.

All of the ranked prospects below also appear on The Board, a resource the site offers featuring sortable scouting information for every organization. It has more details (and updated TrackMan data from various sources) than this article and integrates every team’s list so readers can compare prospects across farm systems. It can be found here.

Mariners Top Prospects
Rk Name Age Highest Level Position ETA FV
1 Bryce Miller 24.9 MLB SP 2023 50
2 Harry Ford 20.4 A+ C 2026 50
3 Cole Young 19.9 A 2B 2027 50
4 Bryan Woo 23.4 MLB SP 2023 45+
5 Emerson Hancock 24.1 AA SP 2023 45
6 Felnin Celesten 17.8 R SS 2029 45
7 Jonatan Clase 21.1 AA CF 2024 45
8 Michael Arroyo 18.7 A 2B 2027 40+
9 Tyler Locklear 22.6 A+ 1B 2026 40+
10 Gabriel Gonzalez 19.5 A RF 2026 40+
11 Prelander Berroa 23.2 AA SIRP 2023 40+
12 Justin Topa 32.3 MLB SIRP 2023 40
13 Tyler Cleveland 22.5 A MIRP 2026 40
14 Lazaro Montes 18.7 R DH 2027 40
15 Taylor Dollard 24.4 AAA SP 2024 40
16 Michael Morales 20.9 A SP 2026 40
17 Ty Adcock 26.4 MLB SIRP 2022 40
18 Jimmy Joyce 24.5 A+ MIRP 2025 40
19 José Caballero 26.8 MLB 2B 2023 40
20 Spencer Packard 25.7 AA LF 2025 40
21 Isaiah Campbell 25.9 AA SIRP 2023 40
22 Darren Bowen 22.4 A SP 2027 35+
23 Darren McCaughan 27.3 MLB SP 2023 35+
24 Ashton Izzi 19.6 R SP 2027 35+
25 Tyler Gough 19.9 A SP 2027 35+
26 Peyton Alford 25.9 AA SIRP 2025 35+
27 Cade Marlowe 26.0 AAA CF 2023 35+
28 Juan Then 23.4 MLB SIRP 2023 35+
29 Devin Sweet 26.8 AA SIRP 2024 35+
30 Travis Kuhn 25.1 AAA SIRP 2024 35+
31 Joseph Yabbour 20.0 R SP 2028 35+
32 Walter Ford 18.5 R SP 2027 35+
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50 FV Prospects

1. Bryce Miller, SP

Drafted: 4th Round, 2021 from Texas A&M (SEA)
Age 24.9 Height 6′ 2″ Weight 190 Bat / Thr R / R FV 50
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Cutter Command Sits/Tops
70/70 45/50 40/45 40/45 45/50 50/55 92-96 / 98

Miller spent his freshman year at Blinn College, then pitched out of the Texas A&M bullpen as a sophomore and junior. Despite sitting 94-97 mph in outings that were often seen by decision-makers in to scout Asa Lacy and Christian Roa, Miller was passed over in the 2020 draft, largely because he was very wild. In 2021, he moved into the Aggies’ rotation, and while his fastball would peak in the 95-98 range, he’d typically settle in at 92-94 as a starter and still had issues with walks. The Mariners drafted him in the fourth round and have deployed him as a starter while altering aspects of his delivery to keep Miller behind the baseball more consistently, which has added to the huge vertical ride on his fastball. His peak velocity also returned and stuck around, as his fastball averaged 96 mph throughout 2022, when Miller coasted through a season split between High- and Double-A. Assigned to Double-A Arkansas again at the start of 2023, it wasn’t long before Miller kicked down the door to the big leagues, and while he’s still a little rough around the edges, his fastball quality has been sufficient for him to beat big league hitters.

Miller isn’t a surgeon but that’s fine, as his type of fastball has a ton of in-zone margin for error because of its shape and life. The same applies to his velocity. He’s actually lost a tick off his fastball compared to 2022, and his velo has continued to trend down, but it’s still blowing big leaguers away and is a legit plus-plus pitch. So long as he’s in and around the zone, he doesn’t need to have precise command to succeed. Miller will occasionally show you good secondary stuff, but most of his other pitches are below-average. He has a mid-80s cutter/slider that doesn’t often have vertical depth, though it does have good length for how hard it is. His upper-70s curveball has more depth and plays nicely with his fastball, but it isn’t a powerful, bat-missing breaker and Miller relies on the fastball to set it up. Miller’s arm swing is long and he sometimes falls off the mound toward first base during his delivery, especially as he tires late in starts. He was somewhat walk-prone in 2022 and lots of scouts thought he ultimately projected in relief. Miller’s fastball isn’t quite as nasty as Spencer Strider‘s and his command isn’t as good as Joe Ryan‘s, but those two represent examples of how, if your fastball is good enough, you can be a good big league starter by leaning on one monster pitch. When you consider that Miller lost a lot of developmental time to the pandemic and being buried on A&M’s depth chart, you can start to get excited about how much potential growth remains for him. He hit the injured list with a blister just before list publication.

2. Harry Ford, C

Drafted: 1st Round, 2021 from North Cobb HS (SEA)
Age 20.4 Height 5′ 10″ Weight 200 Bat / Thr R / R FV 50
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
30/40 55/60 30/50 60/60 30/45 60

Ford is a very explosive, high-upside catching prospect with a rare collection of tools for a backstop, most notably plus-plus bat speed that gives him impact power potential at that position. Tightly wound and muscular, Ford looks incredible during BP and has crude-looking but effective feel for contact in games. It’s not always flush contact, but Ford finds a way to put the ball in play, and his strength enables power that would make him a star if he can indeed stay at catcher.

Though he is twitchy and supremely athletic in other ways, Ford was omitted from the offseason Top 100 because he needed a lot technical development behind the plate. Indeed, Ford was so raw in high school that there was talk of him being drafted as a center fielder. He has tweaked some aspects of his defense and is now catching on one knee (his crouch in high school was comically upright), and his hands and receiving are slowly but steadily improving, but Ford is still a pretty poor ball-blocker and struggles to reach across his body to snare poorly-located pitches. He’s gotten better at trying to pick short-hops in the dirt, which seems like a better way of limiting caroms than moving his body in front of the baseball. He’s still not a lock to stay back there, but he’s improved a fair bit already and is still only 20 years old. At this point, he should be considered better than a 50/50 bet to catch, and he has a non-zero chance of playing an up-the-middle position if it turns out he can’t. Ford will run as fast as 4.1 from home to first and has the speed to give center field a shot if the Mariners are inclined to try.

Bordering on passive, Ford is extremely selective at the plate and has taken advantage of A-ball pitchers’ poor command. His swing is a little grooved through the down-and-in portion of the zone, static enough to consider Ford a future below-average contact hitter despite how he’s performed so far. At catcher, any kind of offensive impact is a big deal, and Ford’s patience and power give him two ways to do it. His hands are lightning fast and powerful, capable of crushing mistakes. He’s not racing to the big leagues or anything, but he projects as a long-term primary catcher and moves into the Top 100 right next to Angels catching prospect Edgar Quero, who has a similar bat-first profile.

3. Cole Young, 2B

Drafted: 1st Round, 2022 from North Allegheny HS (PA) (SEA)
Age 19.9 Height 6′ 0″ Weight 195 Bat / Thr L / R FV 50
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
35/55 45/50 35/50 50/50 40/50 45

Young’s profile has shifted pretty dramatically since he was drafted, as he has added considerable bulk to his frame. As a high schooler, he was among the more polished shortstop defenders in his class and was performing well from a bat-to-ball standpoint on the showcase circuit. He looked like a high-floor middle infield prospect with a modest ceiling. His upper body has become much stronger and Young already has close to average big league raw power, while his increased size has detracted from his defense and has put him at risk of sliding to second base as he climbs the minors. His hands and exchange are still good, and he has a suitable arm for shortstop, but he now lacks the range and bend of the typical big leaguer there.

Young is performing very well at the plate with Low-A Modesto, walking more than he strikes out and K’ing at just a 13% clip. His underlying contact rates are close to the middle of the big league middle infield pack at around 80%. There are some aspects of his swing that may require adjustment over time. For instance, Young’s momentum is almost always taking him down the first base line as he swings, and his bat path tends to loop through the bottom of the zone. Despite this, he’s been able to cover the outer third consistently so far, and he hasn’t yet been exploited by the up-and-away fastballs that hitters with swings like this tend to struggle against. Young’s work in the weight room has led to an uptick in his raw power, but it’s still a shade below average and he’s now close to maxed out. He’s likely to mature into a well-rounded combination of contact and power that gets amplified by his feel for the strike zone, which is excellent. He’s a very stable everyday middle infield prospect.

45+ FV Prospects

4. Bryan Woo, SP

Drafted: 6th Round, 2021 from Cal Poly (SEA)
Age 23.4 Height 6′ 2″ Weight 205 Bat / Thr R / R FV 45+
Tool Grades (Present/Future)
Fastball Slider Changeup Cutter Command Sits/Tops
60/60 40/45 40/55 40/45 45/55 93-96 / 98

Woo was an offseason Pick to Click who has been pressed into major league duty ahead of schedule due to injuries in the big club’s rotation. He was a 2021 pre-draft favorite here at the site because of his ultra-athletic delivery and his fastball’s underlying characteristics, which, with his mid-90s velocity, were nearly certain to give him at least one impact pitch. A Tommy John prevented him from debuting until late in 2022, when he made 16 starts during the regular season and finished in the Fall League. In 2023, his quick promotion to Seattle has forced Woo to lean on his fastball(s) at an unsustainable rate because the rest of his repertoire is still developing. Between his four- and two-seamers combined, Woo is using his heater 75% of the time as of list publication. There isn’t a qualified starter anywhere near that mark.

The good news is that there’s reason to project on his secondary stuff. Woo’s athleticism and arm action portend significant changeup growth over time, and it wouldn’t surprise me if that’s eventually his best secondary pitch; his cambio usage was climbing in the couple of starts leading up to list publication. He has a mid-80s spike slider that is currently operating as his most-used non-fastball offering, and the quality and location of that pitch varies wildly. There’s evidence that Woo has begun using a cutter in games, beginning with his late-June start against the Nationals. Several of his breaking balls were harder than his usual sliders and it didn’t look like he was using the spike grip he uses for his slider to throw them. You can see things are still rather magmatic here. Woo is developing on the fly and it’s remarkable that he’s had success at the big league level despite this. I’d love to 50 him and put another Pick to Click feather in my cap, but I feel like I’d be putting my thump on the scale. There’s still too much hay to be made with his secondary stuff to do that at this time, though he’s clearly a good pitching prospect and I think over time he’ll look more like a slam dunk mid-rotation starter.

45 FV Prospects

Drafted: 1st Round, 2020 from Georgia (SEA)
Age 24.1 Height 6′ 4″ Weight 213 Bat / Thr R / R FV 45
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
45/50 55/60 45/50 55/60 35/55 93-96 / 97

Hancock’s 2021 season was limited due to shoulder issues that first caused him to miss about a month in the middle of the summer and then to be shut down for the season in September. He then had a lat strain during 2022 spring training and didn’t break camp, but he was still able to make 20 starts and work about 100 innings. So far in 2023, Hancock has been healthy and effective, but not dominant, at Double-A Arkansas. He may have augmented his breaking ball, as that pitch is a few ticks harder now than last year (sitting 86 mph) and looks more like a cutter than a true slider, while the rest of Hancock’s stuff looks the same. His changeup remains his best bat-missing pitch because, despite its flat approach angle, his fastball’s sink and tail action tends to find wood unless Hancock really elevates it. He isn’t a slam dunk mid-rotation prospect and is more of a contender’s no. 4/5 starter.

6. Felnin Celesten, SS

Signed: International Signing Period, 2023 from Dominican Republic (SEA)
Age 17.8 Height 6′ 0″ Weight 160 Bat / Thr S / R FV 45
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
20/50 40/55 25/55 55/50 40/50 60

Celesten was the third-ranked prospect in the 2023 international class and signed for nearly $5 million in January. He’s a well-rounded, switch-hitting shortstop prospect who has a chance to mature in the Goldilocks Zone, where he adds meaningful power while staying at short. His feet, hands and actions are all fits there, while he’ll flash big power from both sides of the plate. Celesten came to the states for a little bit during minor league spring training and then quickly returned to the Dominican Republic to train and begin his career in the DSL. He did not look especially good with the bat during his little bit of stateside time, but he wasn’t here long enough to be confident that his hit tool will actually be a problem. He suffered a hamstring strain before the DSL season, an injury expected to cost him a couple of months. The Mariners have been inconsistent participants in fall instructs during the last few years, but they played games during last year’s autumn period, so perhaps the industry will get a multi-week look at Celesten in the fall.

7. Jonatan Clase, CF

Signed: July 2nd Period, 2018 from Dominican Republic (SEA)
Age 21.1 Height 5′ 8″ Weight 175 Bat / Thr S / R FV 45
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
30/35 45/50 40/45 80/80 45/50 40

Clase had a cartoonish start to his 2023 season, posting a 198 wRC+ at Everett before a promotion to Arkansas. He has already set a career-high in homers halfway through the season. Still relatively new to switch-hitting, Clase’s right-handed swing remains extremely raw and much less dynamic than his lefty cut, which is explosive but flawed. Clase is striking out a ton and wholly unable to get on top of high fastballs. But he’s also incredible strong for his size, he’s an explosive rotational athlete whose swing often finishes with his bat in the dirt behind him, and he has the ability to dip and rip low pitches with authority. His feel for center field isn’t great, especially on balls hit in front of him. Elite speed helps mitigate this issue enough to profile in center and will enable Clase to make an impact on the bases. Even with a scary hit tool, Clase’s tools are too big to consider him a Guillermo Heredia 에레디아 type of fifth outfielder; he is much too dangerous a mistake hitter (do not hang a breaking ball to this guy) and pinch-running threat in close games. He’ll likely have some seasons with 15 or so homers if he gets enough at-bats, and there might yet be some growth to his right-handed feel for contact.

40+ FV Prospects

Signed: International Signing Period, 2022 from Colombia (SEA)
Age 18.7 Height 5′ 8″ Weight 160 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
25/55 40/45 20/45 60/60 40/55 50

Arroyo is an extremely difficult evaluation because in many ways, his data and visual assessment don’t jive. Visually, I am scared of Arroyo’s hit tool. He has a bat wrap and a late hitch that I fear will make him habitually late against velocity, and his closed stride looks like it will make it tough for him to cover the down-and-in portion of the zone. To my eye, his swing is geared for contact with low-and-away pitches and that’s kind of it. On paper, he’s been a much better hitter than that during his young minor league career. He’s posted a .332/.461/.533 line so far as a pro, run an 80% contact rate each of the last two seasons, and as of list publication, is sporting a 14% barrel rate and a 43% hard-hit rate at Modesto, all at age 18. Arroyo definitely has plus bat speed, and it’s possible that, at a short-levered 5-foot-8, what looks to my eye like mechanical length is made sustainable by Arroyo’s (lack of) size. Still, I’m more inclined to trust my eyes than I am to care about DSL data and two weeks of Cal League performance. I think there’s a swing change that could unlock better plate coverage, and it’s possible I’m just wrong, but I wouldn’t be confident taking Arroyo back as the centerpiece of a blockbuster trade at this stage.

Tightly wound, I’m more sure Arroyo isn’t a shortstop. He has plus range but can’t position his body to make all the throws from there. He has the hands, range, and arm strength to play the other infield positions and might even have the speed for center field. There are some exciting elements here, and Arroyo is definitely one of the better prospects in Seattle’s system, just not a projectable potential star.

Drafted: 2nd Round, 2022 from VCU (SEA)
Age 22.6 Height 6′ 1″ Weight 210 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
30/45 65/65 30/55 30/30 30/40 50

The experiment with Locklear at third base is already over, but it wasn’t realistic to expect him to fit over there and it hasn’t impacted his evaluation. What has caused me to slide Locklear down an FV tier compared to his pre-draft grade is his relatively inability to pull the ball. He still has incredible wrist-flicking power and enough strength to do damage to the opposite field, but I worry upper-level velo and pitch execution around his hands will be tough for him to time. It’s extremely difficult for a right/right first baseman to make a significant big league impact, and basically any hole in one’s offensive profile is damning, but Locklear’s combination of strike zone discipline and strength-driven power give him considerable OBP and SLG potential.

It’s rare for short-levered hitters to have this much pop (and also to have a hole on the inner third), and Locklear’s 2023 hard-hit rate (a whopping 48% as of list publication) and peak exits velos are significantly higher than the big league average, though close to average for a starting big league first baseman. Locklear’s rate and quality of contact is a bit below what I expected coming out of college, and there’s a definite gap between his raw power and game power at this stage. His swing hasn’t been altered thus far in pro ball, and perhaps something can be done about this detail. He tracks pitches like a bird of prey and, unlike a lot of hitters whose chase rates are as low as Locklear’s (25%), his overall swing rate is hovering around league average, indicating he has actual feel for the zone. There’s still enough here to consider Locklear a second-division first base prospect, and it’s important to be sensitive to potential mechanical changes that could enable a real breakout.

Signed: International Signing Period, 2021 from Venezuela (SEA)
Age 19.5 Height 5′ 10″ Weight 180 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
25/50 50/55 20/50 45/40 35/60 55

Gonzalez is a precocious young corner bat with a potent hit/power combination and, aside from his plate discipline and one aspect of his plate coverage, a fairly well-rounded offensive skill set. He’s already quite physically mature and much less projectable than the typical 19-year-old corner outfield prospect, but his physical maturity is part of what’s helping him punish the ball with power. Gonzalez also has pretty advanced barrel feel. His compact stature and quick wrists make him tough to beat on the inner half and at the top of the zone, but his front side is stiff and upright throughout his swing, and he struggles with pitches down and away from him. He’s also been quite chase-prone as a pro (he’s chasing at a nearly 40% clip so far this year), which, combined with his plate coverage issues, causes him to swing inside slider after slider. Righty-hitting corner guys who lack plate discipline are scary prospects, but Gonzalez is very young and some of his issues at the plate might have an easy fix via a more flexible lower half or by crowding the plate. The bat speed and barrel feel combo is enough to push Gonzalez above a typical corner bat prospect with warning signs like his.

11. Prelander Berroa, SIRP

Signed: July 2nd Period, 2016 from Dominican Republic (MIN)
Age 23.2 Height 5′ 11″ Weight 170 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Fastball Slider Command Sits/Tops
70/70 60/60 30/35 96-98 / 101

Originally a Twin, Berroa was traded to San Francisco as part of the awful Sam Dyson trade, then was traded to Seattle last May for Donovan Walton. As the prophecy foretold, Berroa was finally moved to the bullpen after making five starts at the beginning of 2023. He has joined the legion of wild arms who are now leading with their slider and using their fastball as a two-strike chase pitch. The line on his fastball, when located at the letters, sets his slider up to freeze hitters and then dive into the zone after they’ve given up on it. It’s not going to be an efficient operation, but Berroa has plus-plus arm strength and a nasty vertical breaking ball that are both capable of missing bats. If he can become a bit more mechanically consistent, he’ll work in higher-leverage spots.

40 FV Prospects

12. Justin Topa, SIRP

Drafted: 17th Round, 2013 from LIU Brooklyn (PIT)
Age 32.3 Height 6′ 4″ Weight 200 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Changeup Cutter Command Sits/Tops
60/60 60/60 40/40 50/55 40/40 94-96 / 98

Yes, the 32-year-old Topa was still rookie-eligible entering the year because he’s had trouble staying on the field. His journey has included two Tommy Johns, a multi-year stint in Indy Ball, renewed elbow issues in 2021 that would eventually lead to a flexor tendon surgery in 2022, and than an ankle contusion at the end of last season. He’s already thrown twice as many big league innings in 2023 as he did in parts of three big league seasons prior. Healthy Topa is really nasty. He has an upright, sidearm delivery that generates mid-90s velo, which he has long paired with a low-80s lateral slider. The last two years he’s begun to fold in a few changeups and, in 2023, a new, low-90s cutter. All three of his harder pitches are generating an above-average groundball rate, with his primary fastball getting grounders at a whopping 72% clip. There are some situations when you need that groundball and would rather have Topa out there than anyone else in your bullpen, even though he isn’t a bat-missing reliever.

13. Tyler Cleveland, MIRP

Drafted: 14th Round, 2022 from Central Arkansas (SEA)
Age 22.5 Height 6′ 3″ Weight 185 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
35/40 55/60 45/55 35/60 83-85 / 89

Cleveland is a submarine starter with a tailing mid-80s fastball and sweeping mid-70s slider. He is extremely athletic and has fantastic command of both pitches. While his velocity is near the bottom of the scale, it could tick up in the bullpen and Cleveland’s command weaponizes his slider in a significant way. He is a high-floor relief prospect who has a shot to take the Sergio Romo/Darren O’Day track where he pitches in a core relief role forever despite not throwing very hard.

14. Lazaro Montes, DH

Signed: International Signing Period, 2022 from Cuba (SEA)
Age 18.7 Height 6′ 3″ Weight 240 Bat / Thr L / L FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
20/30 60/70 25/60 40/20 20/20 60

I was extremely high on Montes as an amateur and some measure of that report was correct. He has incredible power for a teenage hitter (his first ACL homer left the bat at 118 mph) and, even though Montes has filled out much more quickly than I anticipated and is close to maxed out, he may yet grow into more. His swing is just so long and bottom-hand drive that I think it’s going to be tough for him to hit. Given his size already at age 18, there’s significant risk he’ll lose the mobility to play the outfield before he even reaches the big leagues. He’s already striking out nearly 30% of the time in rookie ball, which is a red flag when it comes to projecting his hit tool. He has very exciting power for a teenage hitter, but I’m inclined to round down based on how hitters with these warning signs tend to pan out.

15. Taylor Dollard, SP

Drafted: 5th Round, 2020 from Cal Poly (SEA)
Age 24.4 Height 6′ 3″ Weight 195 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
40/45 55/60 45/45 45/50 35/60 90-93 / 94

Dollard made three 2023 starts before he was shut down with a shoulder injury that cost him the rest of the season and required labrum surgery. He had been tracking as one of the higher-floored prospects in this system. Dollard only sat 86-92 mph during the short, pre-shutdown college season, but has been more comfortably in the low-90s in the two seasons since. His slider is his best pitch and had become his most-used offering, at around 47% usage. Surgical command weaponizes the length of Dollard’s slider, the quality of which some pitch metrics indicate is elite, though visual evaluations have it as merely above average. Dollard’s fastball and slider give him an east/west style of attack reliant on his plus command. His changeup and curveball both move quite a bit but lack power and true plus action. It’s a robust enough repertoire to continue projecting Dollard as a quick-moving, back-of-the-rotation candidate if he returns healthy next season.

16. Michael Morales, SP

Drafted: 3rd Round, 2021 from East Pennsboro HS (SEA)
Age 20.9 Height 6′ 2″ Weight 205 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
30/35 55/60 45/50 35/55 88-92 / 94

When your favorite team drafts a prototypical high school pitching prospect, you hope there’s a Kershaw or a Bumgarner at the end of the rainbow. Sometimes, however, their stuff doesn’t get much better, though they learn to pitch with their current stuff and things turn out okay. This latter track is the path Morales is on. Morales wasn’t an ultra-loose or projectable sort of high schooler — his size and level of athleticism are both more middle-of-the-road, and those are often the things that lead to an big breakout. He still has a low-90s fastball, feel for spin, a suitable changeup, and starter-quality command. He’s now made 40 starts at Low-A with a 23% K% and 9% BB% and is a low-variance fifth starter prospect.

17. Ty Adcock, SIRP

Drafted: 8th Round, 2019 from Elon (SEA)
Age 26.4 Height 6′ 0″ Weight 213 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Cutter Command Sits/Tops
55/60 55/60 40/40 94-97 / 98

Adcock was a college catcher conversion arm who emerged as an upper-90s power relief prospect a full year after he was first draft-eligible. The pandemic and an unfortunately timed Tommy John prevented him from making his pro debut until 2022, when he worked just 18 innings combined between the regular season and a wild Fall League. After a hot 20 innings in the minors this year, the Mariners shuttled Adcock straight from Double-A to the big leagues. He’s thrown strikes at a much better clip than has been the case historically, bullying the zone with his mid-to-upper-80s cutter/slider more than his fastball. That breaking ball’s shape will vary, and Adcock’s best chance to miss a bat is when it has more vertical depth. It’s possible he’s just scratching the surface having thrown just 20 annual innings since 2018.

18. Jimmy Joyce, MIRP

Drafted: 16th Round, 2021 from Hofstra (SEA)
Age 24.5 Height 6′ 2″ Weight 210 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
45/50 45/50 55/60 30/40 92-94 / 95

Joyce is a plus on-mound athlete who, after a big hip turn, gets deep into his lower half as he bounds down the mound, giving his fastball weird, flat angle, especially for a running two-seamer. It bores in on righties with action that causes hitters to drive the baseball into the ground, and Joyce generated a 60% groundball rate in 2022 and has a 65% GB rate so far in 2023. He also has a plus changeup that he wasn’t executing with great consistency at Hofstra, with the pitch often sailing high and to Joyce’s arm side. Now it’s the inverse, as Joyce tends to yank the changeup toward his glove side; it plays more like a two-seamer that runs back over the plate, sometimes sinking enough to slip beneath barrels. He also has a sweeping low-80s spike curveball that has lovely depth but is easy to identify out of the hand because it looks so much different than his sinker. The raw material for that pitch to be good is in there, and Joyce is coming out of a small program. He’s experiencing a little velo spike so far in 2023, up two ticks from last year, though he’s only made a handful of starts as of list publication and might be abnormally fresh. There are starter ingredients here but somewhat limited breaking ball utility and middling command, so Joyce projects in a multi-inning relief role.

19. José Caballero, 2B

Drafted: 7th Round, 2017 from Chipola JC (FL) (ARI)
Age 26.8 Height 5′ 11″ Weight 165 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
50/50 35/35 30/30 60/60 50/50 50

Caballero is on pace to have a 3-WAR season as Seattle’s part-time second baseman and reserve SS/3B, but over time, he projects as more of a 1-WAR annual performer whose contribution to the team is as much about his competitive edge as it is his skill level. Caballero is perhaps the best in baseball at leveraging the pitch clock and timing his entry into the batter’s box in such a way as to make the opposing pitcher vulnerable to a violation, or to cause the pitcher to come set before Caballero has visually addressed the mound. It sometimes puts the opposing pitcher on tilt, and I can’t decide if it’s bush league or brilliant, but like the Patrick Beverlys and Tie Domis of the world, Caballero is the kind of player you love when he’s on your team and hate when he’s not. His best offensive attribute is his plate coverage, which is especially impressive at the top of the strike zone. So long as the Mariners remain thin with viable shortstops, he’ll likely play a utility infield role.

20. Spencer Packard, LF

Drafted: 9th Round, 2021 from Campbell (SEA)
Age 25.7 Height 6′ 1″ Weight 205 Bat / Thr L / R FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
35/55 50/50 30/45 30/30 30/40 40

Packard played a year at Arizona Western before transferring to Campbell, where he spent another three. He was eligible to be picked in 2020 but had the worst month of his amateur career during that brief four-week season, hitting just .164. Even with his 2020 clunker included, Packard had a .324/.453/.504 career line at Campbell. He’s reached Double-A as a career .265/.381/.428 hitter in pro ball, with a 14% BB% and 16% K% combined the last two seasons. While the 25-year-old has modest tools that will likely limit him to a low-end platoon role, he has a very polished approach and a great idea of the strike zone, he can clear his hips and ambush inner-third fastballs, and he has enough power to take fastballs on the outer half into the opposite-field gap. Packard isn’t Rule 5 eligible until after the 2024 season and will act as upper-level corner outfield depth for the next year or two, then be elevated to the 40-man as some of Seattle’s other up/down outfielders run out of options and likely move on.

21. Isaiah Campbell, SIRP

Drafted: 2nd Round, 2019 from Arkansas (SEA)
Age 25.9 Height 6′ 4″ Weight 225 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Command Sits/Tops
55/55 60/60 50/50 93-96 / 97

Campbell was granted a medical redshirt in 2017 because of surgery to remove bone spurs from his elbow. His stuff wasn’t totally back in 2018 and the Angels tried to buy low on the then-redshirt sophomore in the 28th round. He returned to school, his stuff bounced back, and Campbell went in the 2019 second round. He barely pitched in 2020 or 2021 due to the pandemic and a TJ. A move to the bullpen part of the way through 2022 helped Campbell’s stuff tick up, and he’s throwing two ticks harder so far in 2023 than he was on average last season. His delivery and on-mound athleticism are still scary but when he’s been healthy, Campbell has thrown plenty of strikes and has two good pitches in his heater and nasty vertical slider. He’s currently on the Mariners’ 40-man and is a decent bet to debut at some point in the second half of 2023, projecting as a middle reliever.

35+ FV Prospects

22. Darren Bowen, SP

Drafted: 12th Round, 2022 from UNC Pembroke (SEA)
Age 22.4 Height 6′ 3″ Weight 180 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
55/60 50/60 20/50 30/50 94-95 / 96

Bowen is an exciting Division-II prospect from UNC Pembroke whose per-outing innings count is being brought along slowly at Modesto. Bowen is a college-aged prospect, but he’s still extremely lanky and projectable and is already one of the harder throwers in the system. He’s only working two innings at a time — important context — but Bowen’s fastball is averaging just shy of 95 mph in 2023. His slider has big natural action that will need to be manicured and located more precisely than Bowen has to this point. Watch Modesto games and you’ll see that opposing right-handed hitters have a really hard time parsing his two pitch mix and end up taking front door sliders for strikes. Arm actions as long as Bowen’s aren’t typically well-suited for changeup development, but he’s usually in a great position at foot strike and he’s a super loose athlete. For now, he’s a wonderful developmental prospect whose pro career is just underway.

Drafted: 12th Round, 2017 from Cal Poly (SEA)
Age 27.3 Height 6′ 1″ Weight 200 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
30/30 50/50 55/55 55/60 87-91 / 95

McCaughan is a nice upper-level spot start option with a funky, slingin’ three-quarters delivery. He works east and west with sink and tail, and will try to run his fastball in on the hands of right-handed hitters, then bend his slider away from them. His high/arm-side approach with the fastball makes him fly-ball prone even though it’s a sinker. The PCL hitting environment is particularly unkind to guys like this, so don’t read too much into McCaughan’s ERA with Tacoma. His slot helps his slider play against righties, while consistent feel for changeup location thwarts lefties. It isn’t a sexy mix, but McCaughan can really pitch, and he’s a great fit as an up/down starter who’ll come up and throw strikes when you need him to.

24. Ashton Izzi, SP

Drafted: 3rd Round, 2022 from Oswego East HS (IL) (SEA)
Age 19.6 Height 6′ 3″ Weight 165 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Curveball Command Sits/Tops
40/50 50/55 20/50 90-92 / 96

Izzi is a projectable youngster with a low-90s fastball and promising depth on his low-80s breaker. He has been brought along very slowly so far in 2023, only recently emerging in games on the complex. The Mariners gave him a shade over $1 million to sign, and Izzi is the archetypal million-dollar high school arm with room for strength on his frame and natural feel for his breaking ball; the rest is abstract projection.

25. Tyler Gough, SP

Drafted: 9th Round, 2022 from JSerra HS (CA) (SEA)
Age 19.9 Height 6′ 2″ Weight 205 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
45/50 45/50 45/50 50/60 30/45 90-91 / 94

Gough signed for an over-slot $275,000 and is a physically-mature four-pitch righty with plus-plus riding life on his fastball and a precocious changeup. His mid-70s curveball has good-looking depth but lacks bite at present. Gough is having early-career growing pains at Modesto, but it’s the Cal League and that environment is hard on just about everyone. It’s tough to project a ton on his fastball because Gough is already pretty filled out, but there are starter ingredients here.

26. Peyton Alford, SIRP

Undrafted Free Agent, 2021 (SEA)
Age 25.9 Height 6′ 0″ Weight 190 Bat / Thr L / L FV 35+
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
60/60 50/50 20/20 40/40 92-94 / 95

Alford has a left-handed invisiball, a riding 93 mph ghost that has dominated High-A hitters so far in 2023. Alford was essentially demoted from Arkansas to Everett in June of last year because his walks were out of control, but he’s slowly tamped them down and has been great so far this season. Like a short-levered Colin Poche, Alford hides the ball forever and then has a short, vertical arm stroke that imparts backspinning axis on his heater. His smaller stature and T-Rex arms help him to have a low release height, so his fastball has uphill angle as it approaches the plate. All of these traits together make his fastball really hard to get on top of. Fold in an average curveball and you have a solid lefty reliever. Alford also has a changeup, but his arm slot is totally different when he throws it and that’s not gonna cut it at the big league level. He hasn’t been a competent strike thrower for very long, and it’s possible this is a blip and Alford regresses. That’s priced into his FV, rounding down what is otherwise a 40 FV mix.

27. Cade Marlowe, CF

Drafted: 20th Round, 2019 from West Georgia (SEA)
Age 26.0 Height 6′ 1″ Weight 210 Bat / Thr L / R FV 35+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
35/40 50/50 40/45 55/55 40/45 40

Marlowe has hit 20 bombs each of the last few seasons and is on pace to do it again in 2023. He has a narrow approach at the plate that helps him walk a lot and also allows him to do damage when he does make contact, since his swing is geared for lift in the middle of the zone. His stiff front side makes it tough for him to get the bat head on pitches in the bottom third of the zone, and Marlowe does swing and miss quite often. He runs well enough to play center field, but he isn’t great at closing the deal out there, covering a lot of ground but looking awkward at the catch point. He’s on the 40-man and is above-replacement depth because of his center field ability and playable power.

28. Juan Then, SIRP

Signed: July 2nd Period, 2016 from Dominican Republic (SEA)
Age 23.4 Height 6′ 1″ Weight 200 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
45/60 55/60 40/40 40/45 93-96 / 98

Then (pronounced “Ten”) was originally signed by Seattle, then was sent to the Yankees when the Mariners were swapping low-level prospects for 40-man depth at the end of their last competitive window; he was finally being returned in the Edwin Encarnación deal. His repertoire and delivery has been augmented a few times since then, and Then has settled in as a pretty standard three-pitch reliever with a sinker, slider, and changeup. His delivery now looks a lot like Penn Murfee’s except without quite as low an arm slot. There was a time when he’d kiss 100 mph, but currently Then is sitting 94 and bumping 97 with sink and tail, creating a lateral action split with his slider. His command has fallen to a place where I consider him more of an up/down guy than an on-roster middle inning arm.

29. Devin Sweet, SIRP

Undrafted Free Agent, 2018 (SEA)
Age 26.8 Height 5′ 11″ Weight 185 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
45/45 45/45 55/60 45/55 90-93 / 95

Sweet was a 2018 undrafted free agent senior sign who had a 2019 breakout. He’s been stuck in neutral at Double-A Arkansas for three seasons since then, and he deserves a promotion. Sweet’s Bugs Bunny changeup is a stinker and embarasses a lot of hitters as it parachutes into the center of the zone. He sets it up by throwing his fastball way above the zone, so that it and his changeup look identical leaving his hand. A mid-80s cutter, which sometimes has two-planed slider movement, rounds out a three-pitch relief mix that should play in an up/down role. Trick-pitch changeups like Sweet’s tend to be sufficient for single-inning impact.

30. Travis Kuhn, SIRP

Drafted: 19th Round, 2019 from San Diego (SEA)
Age 25.1 Height 5′ 10″ Weight 195 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Command Sits/Tops
55/60 55/60 30/40 93-96 / 98

Kuhn experienced an almost five-tick velocity bump during the dark period between 2019 and 2021, and he’s held that velo spike for the last few seasons, most of which he has spent at Double-A. He has one of the more extreme drop-and-drive deliveries in the minors, as Kuhn’s right shin is nearly flush against the mound as he strides home. It takes incredible lower body strength and flexibility to do this, and it helps Kuhn’s fastball have upshot angle that sneaks above barrels at the letters. Kuhn’s slider quality has backed up a bit in 2023, but it’s still his most-used offering. Even though his stuff and performance has regressed a tad, Kuhn is still a likely up/down relief piece.

31. Joseph Yabbour, SP

Signed: July 2nd Period, 2019 from Venezuela (MIN)
Age 20.0 Height 6′ 0″ Weight 175 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Command Sits/Tops
50/60 40/50 30/40 94-96 / 98

Yabbour was released by the Twins in 2022 having never thrown a pro pitch for them. He signed with the Mariners and has been throwing smoke in the DSL, sitting 95 mph with dome riding life. Even though he’s 19, Yabbour isn’t especially projectable. His release isn’t consistent and neither is his breaking ball, but his arm strength makes him a young name to monitor in a system that’s tended to take velo-only guys and make them better.

32. Walter Ford, SP

Drafted: 2nd Round, 2022 from Pace HS (FL) (SEA)
Age 18.5 Height 6′ 3″ Weight 195 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Curveball Command Sits/Tops
20/40 40/55 25/55 20/40 87-91 / 94

Ford reclassified from the 2023 to the 2022 draft. At peak, he has shown an upshot, mid-90s fastball and a long, lateral slider. My pre-draft evaluation noted that his breaking stuff would need reshaping, but that there was clear feel for spin here, as well as a very projectable, lanky build. Ford has struggled so far and his velocity is way down, with some of his fastballs as slow as 86 mph prior to list publication. He has had some stretches in 2023 when he hasn’t been pitching in games so his delivery could be reworked on the side, and things are not in a great spot right now. He’s purely a bounce-back prospect at this stage.

Other Prospects of Note

Grouped by type and listed in order of preference within each category.

Hitter Pu Pu Platter
Miguel Perez, CF
Ricardo Cova, UTIL
Isiah Gilliam, OF
Robert Perez Jr., RF
Hogan Windish, 1B/2B
Kaden Polcovich, 2B/OF
Alberto Rodriguez, RF
Zach DeLoach, OF

The 22-year-old Miguel Perez isn’t hitting at Modesto, but he’s still extremely projectable and covers a lot of ground in center field. He’s a potential late-bloomer to monitor for physical development, but he’s presently not strong enough to have a viable swing. Cova is now on the complex after two years in the DSL. He’s only 5-foot-8, but he’s strong for his size and can play all over the diamond. He was hit by a pitch on the knee yesterday and removed from the game. Gilliam, 26, has plus switch-hitting power and could be a bench weapon despite a 20-grade hit tool. Robert Perez Jr., 23, has plus power, but his combo of whiffs and poor plate discipline has kept him in this section of the list for a while. It looked like he was developing more patience last year, but his walk rates have regressed. Windish, 24, was a 2022 seventh rounder out of UNC Greensboro. He is hitting for power at Everett while playing a few different positions. Polcovich hasn’t played yet this year (I’m actually not sure why), and has always had an interesting power/speed blend for a switch-hitter; he just doesn’t have a clear position. Rodriguez and DeLoach have some pop but not quite the bat-to-ball skills to make the main section of the list.

Big Five Connections
Brian O’Keefe, C
Tatem Levins, C
Josh Hood, INF

All of these guys have a Philly connection of some stripe. O’Keefe, a St. Joe’s alum, is perfectly fine upper-level catching depth with power. Levins transferred from La Salle to Pitt for his senior year and had a great season. He’s a contact-oriented catcher with an athletic swing and enough ability on defense to be developed behind the dish. He needs to cover the top of the zone a little better. Hood went to Penn and then transferred to NC State for his senior year. He’s a well-built, versatile infielder with 40-grade tools on offense.

Slider Guys
Marcelo Perez, RHP
Jarod Bayless, RHP
Juan Mercedes, RHP
Jorge Benitez, LHP
Stephen Kolek, RHP
Mike Flynn, RHP

Perez is a polished college arm from TCU who is currently sitting 93 with sink and tail at Modesto and commanding his slider. Bayless (no relation to the 13-year veteran combo guard from Arizona) is a low-slot righty specialist type. Mercedes is a slider-heavy starter at Double-A who has good peripherals, but I don’t trust that he actually has good command and he’s at best a 40 athlete. Benitez is a low-slot lefty with a good changeup. Kolek has a standard mid-90s/slider reliever look; his heater plays down due to shape and below-average control. Flynn (no, not that one) was a sinker/slider sixth rounder from 2018 who has remade himself as a low-slot righty with a good slider.

Arm Strength
Juan Burgos, RHP
Troy Taylor, RHP
Natanael Garabitos, RHP

Burgos has a great pitcher’s build and has been sitting 93-96 amid some injury issues at Modesto. Taylor, a 2022 12th rounder from UC Irvine, sits 95 with sink. Garabitos is sitting 96 but still has zero feel for location.

System Overview

The Mariners system is flush with interesting developmental arms, but overall, it’s quite shallow and lacks huge impact up top. Harry Ford has the best chance to be the next homegrown star, but he’s risky and his development is likely going to be slow, as is typically the case with young catchers. Felnin Celesten didn’t look great during his brief stateside jaunt this spring, but he left Arizona quickly and then was injured, so there’s no real evidence to support a re-evaluation there. There are people within the org who love Michael Arroyo, but I’m not ready to stuff the guy just yet, though I’m poised to do so if his swing becomes more dynamic. The Mariners tend to waste little time promoting the guys they like, which is part of why the farm system doesn’t look great on paper — lots of them become big leaguers very quickly.

I would consider the Mariners a data-driven org, especially when it comes to evaluating pitchers. Their farm system is dense with guys who have big measurable breaking ball movement. Their track record of tweaking prospects and fringe big leaguers for the better is long enough now to consider them very good at developing arms. If there’s another Bryan Woo in the system, a guy who is raw developmental material right now but who looks like they have the build and athleticism to take a sizable leap, it’s Darren Bowen.

Even if the Mariners were in the thick of the AL West race right now, it would probably be easy for other teams to outbid them at the deadline. They’re a good ways back of first place in their division and the East is crowding out the Wild Card field. Yesterday, they traded Chris Flexen and Trevor Gott (one of those fringe arms they improved) to the Mets for depth arm Zach Muckenhirn, an indication of their likely posture for the next month. None of the Mariners players on expiring deals are having especially good seasons, though Teoscar Hernández would probably fetch something at the deadline if Seattle wanted to move him. If there’s any solace to be found for Mariners fans in the back half of the summer, it’s that the club is likely to have a big draft. They have three top-30 picks in a loaded class. It’s likely that all of them will be top 10 prospects in this system as soon as they sign, which will make the “high end” of this farm (anyone in the 40+ tier or above) look closer to average in terms of depth and quality.

Eric Longenhagen is from Catasauqua, PA and currently lives in Tempe, AZ. He spent four years working for the Phillies Triple-A affiliate, two with Baseball Info Solutions and two contributing to prospect coverage at Previous work can also be found at Sports On Earth, CrashburnAlley and Prospect Insider.

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7 months ago

Can’t wait to dive in. Any thoughts on Justin Topa? I assume he was left off due to eligibility but he’s not listed as a graduate.

Meg Rowleymember
7 months ago
Reply to  3cardmonty

Actually no! That was a goof – his Board record didn’t get updated after the Brewers trade somehow, and I missed it as I was putting the post together. We’ve updated here and on The Board. Thanks for spotting that!