Top 38 Prospects: Seattle Mariners

Below is an analysis of the prospects in the farm system of the Seattle Mariners. Scouting reports are compiled with information provided by industry sources as well as my own observations. For more information on the 20-80 scouting scale by which all of our prospect content is governed, you can click here. For further explanation of the merits and drawbacks of Future Value, read this.

All of the numbered prospects here also appear on The Board, a resource the site offers featuring sortable scouting information for every organization. It can be found here.

Mariners Top Prospects
Rk Name Age Highest Level Position ETA FV
1 Julio Rodriguez 19.2 A+ RF 2022 60
2 Jarred Kelenic 20.7 AA CF 2021 60
3 Logan Gilbert 22.9 AA RHP 2021 55
4 Evan White 23.9 AAA 1B 2020 50
5 George Kirby 22.1 A- RHP 2022 45+
6 Noelvi Marte 18.4 R SS 2023 45+
7 Justus Sheffield 23.9 MLB LHP 2020 45
8 Kyle Lewis 24.7 MLB RF 2020 45
9 Cal Raleigh 23.3 AA C 2021 45
10 Justin Dunn 24.5 MLB RHP 2020 45
11 Sam Delaplane 25.0 AAA RHP 2021 40+
12 Brandon Williamson 22.0 A- LHP 2023 40+
13 Juan Then 20.1 A RHP 2021 40+
14 Wyatt Mills 25.2 AA RHP 2020 40+
15 Jake Fraley 24.8 MLB LF 2020 40
16 Isaiah Campbell 22.6 R RHP 2023 40
17 Braden Bishop 26.6 MLB CF 2020 40
18 Jonatan Clase 17.8 R CF 2024 40
19 Gerson Bautista 24.8 MLB RHP 2020 40
20 Joey Gerber 22.9 AA RHP 2021 40
21 Elvis Alvarado 21.1 A RHP 2021 40
22 Carter Bins 21.9 A- C 2023 40
23 Ljay Newsome 23.4 AAA RHP 2021 40
24 Josias De Los Santos 20.7 A RHP 2022 40
25 Devin Sweet 23.5 A+ RHP 2022 35+
26 Yohan Ramirez 24.9 AA RHP 2020 35+
27 Jorge Benitez 20.8 A- LHP 2022 35+
28 Damon Casetta-Stubbs 20.7 A+ RHP 2023 35+
29 Aaron Fletcher 24.1 AA LHP 2022 35+
30 Raymond Kerr 25.5 AAA LHP 2021 35+
31 Milkar Perez 18.4 R 3B 2023 35+
32 Kristian Cardozo 17.4 R RHP 2025 35+
33 Luis Liberato 24.3 AAA CF 2020 35+
34 Austin Shenton 22.2 A 3B 2022 35+
35 Sam Carlson 21.3 R RHP 2022 35+
36 Levi Stoudt 22.3 R RHP 2023 35+
37 Ty Adcock 23.1 R RHP 2022 35+
38 Jake Haberer 25.1 AAA RHP 2020 35+
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60 FV Prospects

Signed: July 2nd Period, 2017 from Dominican Republic (SEA)
Age 19.2 Height 6′ 3″ Weight 225 Bat / Thr R / R FV 60
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
25/60 60/65 25/60 40/40 45/50 55/55

Like most Millenials, I share account passwords with friends and family to create a Megazord collection of streaming services while only actually paying for one or two. One of these shared logins is for a DAZN account I procured in order to enjoy the platform’s boxing archive, only to discover it had several classic MLB games as well. Among these is footage of Miguel Cabrera’s big league debut, which I put on one fall night as I prepared to cut up Fall League video of Julio Rodriguez taken earlier in the day. As I split my attention between a fresh-faced Miggy and a young Julio, I noticed a rare similarity: front foot variation. Some hitters are capable of altering their stride direction based on pitch location, perhaps best exemplified by a famous GIF of Cabrera hitting home runs on pitches in six very different parts of the strike zone. In that GIF you can faintly make out how Cabrera’s footwork varies on several of those swings, and though he doesn’t do it consistently yet, Julio shows glimpses of this same seemingly innate aptitude, especially his ability to open up, clear his hips, and wreck pitches on the inner half.

He can be fooled by sweeping breaking balls that make him want to open up and pull the ball, and he’ll swing at inside sliders that finish away from him, but other than those consistent issues, Rodriguez is a very mature hitter, with a mature personality and body to match. He excelled despite Seattle’s very aggressive full-season assignment, a move I was skeptical of, and had an impressive Fall League as an 18-year-old. He’s already a 40 runner (I had him timed in the 4.4s throughout Fall League), which means he is ticketed for right field rather than center, but the bat is real. I have plus hit and power projection here and I know scouts who have a 70 on the bat, though his approach and the way his head was flying out during some of his AFL at-bats stopped me from going that heavy with my hit tool grade. I think he’s going to come up quickly and be an All-Star outfielder and the affable face of the franchise.

Drafted: 1st Round, 2018 from Waukesha West HS (WI) (NYM)
Age 20.7 Height 6′ 1″ Weight 196 Bat / Thr L / L FV 60
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
45/60 60/60 45/55 55/50 45/45 60/60

It was an injury-laden year for Kelenic (a wrist and ankle during the summer), who was supposed to pick up Fall League reps until those was delayed by wisdom tooth extraction and then ultimately squashed by back tightness. Despite that, and especially in spite of the wrist injury, the beefcake Wisconsinite hit .291/.364/.540 with 23 dingers and 20 steals across three levels, and reached Double-A as a young 20-year-old. Kelenic is absolutely jacked but it hasn’t detracted from his twitch, nor has his size borrowed from his range in center field, which is suitable if unspectacular for the position.

The carrying tool here is the bat, which has been the case since Kelenic was 15. Like most elite prospects he’s been one of the — if not the — best hitters his age from the time scouts began to see him, and Kelenic hit elite prep pitching all throughout high school. He is short to the ball with power, and can just turn his hands over and catch heaters up, in, or both, which bodes well for him against a pitching population that is working up there with increasing frequency. The .540 SLG% from 2019 is a bit above what’s realistic going forward, largely because there’s just no more room for mass on the body. As is the case with most hitters evaluated in this stratosphere, reports of Kelenic’s competitiveness and work ethic are strong, and have been since he was in high school. In fact, one scout on the amateur side thought he was too intense at times, sort of in the Jimmy Butler realm of teammate interaction, but I haven’t heard anything like that lately. He’s much more stick than glove, but Kelenic looks like an All-Star center fielder who’s rapidly approaching Seattle.

55 FV Prospects

Drafted: 1st Round, 2018 from Stetson (SEA)
Age 22.9 Height 6′ 5″ Weight 195 Bat / Thr R / R FV 55
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
50/55 45/50 50/55 45/50 50/60 91-94 / 96

Last year I wrote about the possibility that Gilbert would experience a velo rebound in pro ball because I thought he had been overtaxed at Stetson. He was sitting 92-96 as a rising sophomore on the Cape, but often sat 90-94, and sometimes 88-91, throughout his starts the following spring. Last year he was again up to 96 but sat 91-94, about the halfway mark between his peak and nadir as an amateur. Considering how readily pitchers lose velo in pro ball, that’s still a win for Seattle. While all of Gilbert’s secondary pitches are average and flash above, I think his command will enable them to play above their raw grades, which, combined with what the innings count could be because of his frame and how efficiently he works, will still make him an above-average WAR generating starter.

50 FV Prospects

4. Evan White, 1B
Drafted: 1st Round, 2017 from Kentucky (SEA)
Age 23.9 Height 6′ 3″ Weight 205 Bat / Thr R / L FV 50
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
50/55 55/55 45/50 60/55 60/70 55/55

White’s pre-draft skillset was tough for some teams to wrangle. All of the window dressing — plus-plus first base defense, plus speed, a backwards hit/throw profile — was nice but ultimately, some teams saw a first baseman without sufficient power. After they drafted him, the Mariners made subtle changes to his lower half, drawing his front knee back toward his rear hip more than he did at Kentucky, and taking a longer stride back toward the pitcher. White is more often finishing with a flexed front leg now, which has helped him go down and lift balls in the bottom part of the strike zone by adjusting his lower half instead of his hands. The power output improved and is supported by the measurable underlying data. Now that he’s signed a pre-debut deal, it’s very likely that White breaks camp with the big club, and he projects as a solid everyday first baseman.

45+ FV Prospects

5. George Kirby, RHP
Drafted: 1st Round, 2019 from Elon (SEA)
Age 22.1 Height 6′ 4″ Weight 210 Bat / Thr R / R FV 45+
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
50/55 40/45 50/55 45/55 55/70 91-96 / 97

If you tally up Kirby’s three years at Elon, his summer on the Cape, and his brief pro debut, he has a 307-to-51 strikeout-to-walk ratio over 276 innings since 2017. That’s a 4% walk rate, and in Kirby’s most recent calendar year of innings, it has been a microscopic 1.3%. While his pre-draft velocity was strong (touching 97, often 93-95 early, 91-94 late in starts), his secondary stuff was very average. His slider and curveball (the latter is better) ran together a bit, and his changeup had inconsistent finish. But often, elite command of what is a 55-grade pitch in a vacuum leads to elite results (see: Bieber, Shane), and I think that sort of secondary pitch effectiveness is possible for Kirby.

One of Seattle’s stated post-draft goals for the right-hander was to make him stronger. In 2020 spring bullpens, Kirby looked noticeably thicker and stronger, and he is indeed throwing harder, touching 99 mph several times in Peoria side sessions. Logan Gilbert threw very hard in a similar setting the year before, and though his in-season velo band was beneath his pre-season bullpens, he was still above the prior year’s range. The difference is the obvious change in Kirby’s body. I expect something similar to Gilbert’s trajectory here (and for Juan Then, who appears later on this list and was also throwing much harder in the spring before baseball shut down). Even with fairly vanilla secondary stuff, mid-90s heat and Kirby’s potential for elite command gives him a mid-rotation ceiling.

Signed: July 2nd Period, 2018 from Dominican Republic (SEA)
Age 18.4 Height 6′ 1″ Weight 180 Bat / Thr R / R FV 45+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
20/50 50/60 25/60 60/55 40/50 60/60

When it comes to both the broad, back-of-the-house view of his amateur profile and his promotion/big league time horizon, Marte’s career has mimicked Julio Rodriguez’s so far. He was a bigger, more physical signee than is typical for the international market, the sort most teams would not hesitate to debut in domestic rookie ball. And like Rodriguez, the Mariners allowed Marte to spend his first pro summer dominating competition that simply didn’t challenge him (the average DSL fastball velo last year was 88 mph), which led to a .309/.371/.511 line. Marte had a chance to earn an aggressive assignment with a great 2020 spring (probably not Low-A, but perhaps a summer Northwest League placement), putting him on a relative fast track for a teenage hitter, though like the rest of baseball, that possibility in now on hold.

From an individual tools and skills perspective, Marte’s peers are elite high school players. As an amateur, there was uncertainty surrounding his hands, actions, and general ability to stay on the infield, but pro looks have been more favorable, backed by enough arm strength to hide potential future range deficiencies. My previous research into shortstop size has shown that most teenage prospects gain about 30 pounds between when they’re 18 and 21 years old, which puts Marte’s baseline body projection in the Willy Adames/Trevor Story realm, or about 210 pounds. So long as his hands have indeed improved, that’s a pretty favorable comp for his body/range-based fit at short. It means there’s Goldilocks Zone power/defensive spectrum potential here, as Marte already has 50-grade raw power at age 18 and will probably have at least a full grade more at maturity. His TrackMan power metrics (they’re over on The Board) are in the 40/45 range right now because Marte’s swing elements are not always well-timed. They are, however, very athletic. The big leg kick (which Marte is balanced enough to utilize), the little bit of bat wrap to create some loop and lift, and the ability to move the barrel around the zone are all encouraging swing elements, but we really don’t know a lot about Marte’s bat-to-ball skills right now because he just hasn’t faced good pitching yet. There’s clearly huge ceiling here and I have Marte in the same FV tier Zac Veen, my highest-ranked prep amateur right now.

45 FV Prospects

Drafted: 1st Round, 2014 from Tullahoma HS (TN) (CLE)
Age 23.9 Height 5′ 10″ Weight 195 Bat / Thr L / L FV 45
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
55/55 60/60 50/55 40/45 89-94 / 96

The roller coaster prospectdom of Justus Sheffield may finally be reaching its terminus. Several repertoire changes, two trades (and the scrutiny that comes with that), fluctuations in his walk rate, some injuries (most notably shoulder stiffness in 2018), and mixed performance at the upper levels have caused a constant need for re-evaluation. The latest of these many developments is a logical shift, given Sheffield’s sinker-friendly arm slot, to a two-seam look on the fastball. Sheffield’s 2020 spring velo was parked in the 89-93 range, but now his fastball has more tailing/sinking action, which dovetails very nicely with the shape of his slider. Sheffield will throw a shorter, curt slider in the zone for strikes (one scout source who saw Sheff this spring thought it might be a separate cutter) and a longer, nastier, bat-missing version that finishes out of the strike zone. This pitch is plus, and was used heavily in Sheffield’s electric spring outings, especially as a back foot out-pitch to righties.

Sheffield’s changeup is also good, but his arm side command of all his pitches is not, so whether he’ll be able to consistently set up the change with well-located fastballs is in doubt. So, too, is Sheffield’s ability to eat innings like a traditional starter because of his hot and cold strike throwing. Some teams just have him projected in the bullpen because of how erratic the strikes have been historically. He’s in the same FV tier as Red Sox righty Bryan Mata, who also has sinker-oriented stuff and significant relief risk.

8. Kyle Lewis, RF
Drafted: 1st Round, 2016 from Mercer (SEA)
Age 24.7 Height 6′ 4″ Weight 210 Bat / Thr R / R FV 45
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
35/40 70/70 55/60 50/45 45/50 60/60

“He’s still a 24-year-old who struck out 29% of the time at Double-A.” This was the general industry response to early drafts I circulated of my Top 100, which had Lewis toward the back of the 50 FV tier where players like Jose Siri and Monte Harrison have been when they’ve made the list. Lewis and his knee (he tore his ACL in 2016) finally looked healthy last year (his swing had more movement, a bigger leg kick, and he seemed to be twisting and bending it with more comfort), and his underlying power data, which I’ll get to shortly, is spectacular. But in some ways what Lewis’ health helped reinforce was skepticism regarding his hit tool. There are folks in baseball who think that on a binary level, Lewis will not hit enough to have a meaningful career. I think he’ll be a high-variance big leaguer, grinding through some frustrating, 1-WAR seasons while he clubs 30-plus bombs in others, similar to Jorge Soler, Domingo Santana, and countless other tantalizing toolsheds who strike out a lot.

As for that underlying power data I promised you, Lewis’ is very encouraging. If you’ve been reading this year’s lists, you know the Southern League offensive environment was very unkind to hitters last season. A source not with Seattle told me that based on his TrackMan/Statcast data, Lewis’ Expected SLG%, was about .100 higher than his actual output, with an xSLG up around .500. He averaged 92 mph off the bat last year and hit 53% of balls in play at 95 mph or above (a 70 on the scale); another source whose team tracked Hard Outs among 2019 minor leaguers (balls in play at 95 mph or up that resulted in outs) told me Lewis made more than 40 of them last year, which was in the top 10 in all the minors. On balance, I think Lewis is a 45, a 1.5 WAR player on average during his years of team control. But he has plus-plus, impact power and could get hot and make some All-Star teams during that span, while other years will be quite lean.

Drafted: 3rd Round, 2018 from Florida State (SEA)
Age 23.3 Height 6′ 3″ Weight 225 Bat / Thr R / R FV 45
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
35/40 55/55 40/50 40/40 45/50 45/45

Teams that had been tracking Raleigh’s framing ability since college have been optimistic about him profiling at catcher for longer than most individual scouts, who see a bigger-bodied guy with mobility issues. Last year, as many orgs have done, Mariners catchers began working on one knee, a move that tends to be favorable for framing but not for throwing, a skill of dwindling importance (for now). Perhaps not coincidentally (or perhaps because we were wrong about Raleigh’s arm grade last year, when we 55’ed it), reports on Raleigh’s arm strength are worse than they were a year ago, though it appears he’s a viable, long-term catcher, if an unspectacular one. If that’s true, then Raleigh has a great chance to be an average everyday backstop thanks to his power and a sentient approach that enables him to hit for it in games and reach base at an above-average clip.

10. Justin Dunn, RHP
Drafted: 1st Round, 2016 from Boston College (NYM)
Age 24.5 Height 6′ 2″ Weight 210 Bat / Thr R / R FV 45
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
50/55 55/55 50/55 45/50 90-93 / 95

Scouts and execs see Dunn settling into one of two outcomes: either he ends up living in the mid-90s as a power reliever, or he sits, as he did in 2019, in the low-90s as an innings-eating No. 4/5 starter. Brendan Gawlowski’s spring look at Dunn, during which the right-hander sat 92-94 over three innings, is perhaps indicative of the former since Dunn rarely worked with his changeup at a time when most starters are working heavily with their tertiary pitch in preparation for the season. Still, I remain somewhat bullish on Dunn’s changeup development. He’s had stretches in the past where it’s been a plus pitch and it’s arguably the best long-term fit with his fastball’s tailing/sinking shape. What I’m less optimistic about is Dunn’s starter stamina. He looked gassed late last year and while into the mid-90s early, was not throwing as hard in subsequent innings this spring. Ideally his fastball lives in at least the 93-96 mph range out of the bullpen and Dunn can be a dynamic, three-pitch reliever. I have his future fastball grade projected as if that’s the outcome.

40+ FV Prospects

11. Sam Delaplane, RHP
Drafted: 23th Round, 2017 from Eastern Michigan (SEA)
Age 25.0 Height 5′ 11″ Weight 175 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Fastball Slider Command Sits/Tops
60/60 70/70 40/45 92-95 / 97

Delaplane has power, vertical action stuff that I think is going to play in a high-leverage relief role. He creates a nearly perfect vertical arm slot by striding wide open, starting on the third base side of the rubber but landing in the middle of the mound. It helps give his fastball plus-plus carry and ride. Delaplane also has a power, Brad Lidge-style slider with late, downward movement. He has less raw arm strength than the Nick Andersons of the world, but the stuff works in the same way, and I think Delaplane will be a reliever of rare quality.

Drafted: 2nd Round, 2019 from TCU (SEA)
Age 22.0 Height 6′ 6″ Weight 210 Bat / Thr L / L FV 40+
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
55/55 50/55 55/60 45/50 40/45 92-95 / 97

It’s not as if Williamson didn’t show plus stuff at TCU; he would be parked at 92-93 in the first inning or two, and flash two plus breaking balls. He did, however, struggle to hold it deep into starts. By the fourth, he was often living in the 88-91 range. After the draft, in one- and two-inning outings, he sat 92-95 with a plus curveball (and fewer, if any, sliders). I’m skeptical that Williamson can hold 92-95 as a starter for a whole season because of how his stuff has waned in the past. He also suffered a severe hip injury while in junior college (he tore both labrums dunking a basketball and needed surgery) that might impact his ability to do it. I buy that the velo will be there in short stints and that both breaking balls, assuming the slider returns, will be plus. As such, I have Williamson projected as a three-pitch power reliever.

13. Juan Then, RHP
Signed: July 2nd Period, 2016 from Dominican Republic (SEA)
Age 20.1 Height 6′ 1″ Weight 155 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
55/60 50/60 40/50 40/50 92-94 / 96

Then (pronounced “Ten”) was originally signed by Seattle, then was sent to New York when the Mariners were swapping low-level prospects for 40-man depth at the end of their last competitive window, before he returned in the Edwin Encarnación deal.

He had a velocity spike over the offseason and, after sitting 91-95 and topping at 96 last year, was up to 99 mph in the bullpen this spring before baseball ceased operations due to the pandemic. Similar to the way Vanderbilt and Kyle Wright found an extra gear for his fastball before the draft, a lower, more naturally comfortable arm slot for Then is part of what seems to have brought this about. Last year, his well-located sliders were plus and the rest of his repertoire below, but he’s lanky and loose, and quite smooth, so that stuff has been at least somewhat projectable. How the lower slot impacts the secondaries and command we won’t know until after Then has taken the new delivery for a spin, but even if things go awry, the velo bump everyone’s been hoping for has seemingly arrived, so a late-inning reliever outcome is now in play.

14. Wyatt Mills, RHP
Drafted: 3rd Round, 2017 from Gonzaga (SEA)
Age 25.2 Height 6′ 3″ Weight 175 Bat / Thr R / R FV 40+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
55/55 60/60 45/50 50/55 92-94 / 95

At the very least, Mills profiles as a good, sidearm “look” reliever who can enter the middle of the game and present hitters with a visual conundrum because of his sidearm slot. His combo of repertoire depth and command are both rare for a reliever, and I think he has a chance to have some peak years like Luke Gregerson, Steve Cishek, Brad Ziegler, or other low slot relievers who closed in recent seasons have had. The statistical case for it — 30% strikeout rate, 54% groundball rate — is strong and Mills has better surface-level stuff than most sidearm relievers do.

40 FV Prospects

15. Jake Fraley, LF
Drafted: 2nd Round, 2016 from LSU (TBR)
Age 24.8 Height 6′ 0″ Weight 195 Bat / Thr L / L FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
50/50 45/45 35/40 55/55 50/55 40/40

Fraley is officially in tweenersville. He plays a fine center field but he’s not such a black hole that it makes up for his lack of power on offense and enables him to profile. Perhaps plus corner defense with a slightly better hit tool than I’ve projected means Fraley can be a platoon 45 FV, but I think enough puzzle pieces with power are floating around that he ends up a Ben Gamel style, luxury bench outfielder.

16. Isaiah Campbell, RHP
Drafted: 2nd Round, 2019 from Arkansas (SEA)
Age 22.6 Height 6′ 4″ Weight 225 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
50/50 50/55 45/50 40/45 40/50 90-93 / 96

Campbell was granted a medical redshirt in 2017 because of surgery to remove bone spurs from his elbow. His stuff was not 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 was ridden pretty hard at Arkansas, and the Mariners chose not to run him out after the draft. We don’t yet know what changes might be made to his repertoire, which was full of average stuff in college. He projects as a No. 4/5 starter.

Drafted: 3rd Round, 2015 from Washington (SEA)
Age 26.6 Height 6′ 1″ Weight 190 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
40/40 50/50 40/40 70/70 70/70 55/55

Bishop remains strangely snakebitten by injury, the latest and most bizarre of which was a 2019 lacerated spleen. He’s still a glove-first, bench outfield prospect.

Signed: July 2nd Period, 2018 from Dominican Republic (SEA)
Age 17.8 Height 5′ 8″ Weight 150 Bat / Thr L / R FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
25/55 40/45 20/40 70/70 45/60 45/45

Clase packs quite a punch for someone his size, and his swing is very short but also geared for some lift. He has a relatively projectionless build, but part of that is because he’s added a bunch of muscle since signing and is now built like a little tank. His speed gives him a shot to be a special center field defender, while the contact feel and seemingly mature idea of the strike zone might weaponize the speed on the bases. There’s a right tail, everyday center field outcome in here.

Signed: July 2nd Period, 2012 from Dominican Republic (BOS)
Age 24.8 Height 6′ 4″ Weight 195 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
70/70 50/50 45/45 35/35 92-97 / 99

This is another of several older relief prospects in the system, one whose report you’re probably familiar with by now. Bautista was part of Seattle’s return in the Díaz/Canó trade; the Mets acquired him from Boston for Addison Reed at the 2017 trade deadline. He’s an arm strength-dependent reliever (96-99 mph) who’ll likely lose list eligibility as soon as we have baseball again. He’s erratic, but as long as he has crude control he’ll bully hitters with his fastball and 84-87 mph slider in a middle relief role.

20. Joey Gerber, RHP
Drafted: 8th Round, 2018 from Illinois (SEA)
Age 22.9 Height 6′ 4″ Weight 215 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
60/60 50/55 40/45 40/40 92-95 / 96

Other than the odd, chicken wing arm action Gerber uses to unfurl his stuff, he has a pretty standard mid-90s heat/power slider relief profile. The fastball gets on hitters more quickly than they expect, and it comes in at a flat angle that hitters also seem to struggle with. He might be up in September.

Signed: July 2nd Period, 2015 from Dominican Republic (WSN)
Age 21.1 Height 6′ 3″ Weight 183 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Command Sits/Tops
60/70 40/50 40/50 92-95 / 98

A converted outfielder, Alvarado was up to 100 during extended and sat in the mid-90s with bat-missing movement throughout the rest of the summer. He’ll flash an occasionally nasty slider but it’s not consistent right now, nor is his strike-throwing, but of course he hasn’t been pitching for all that long. He’s a 2020 40-man add and will have to develop pretty quickly to merit a 40-man spot this winter, but Seattle has had success developing pitching lately and this guy has big ceiling if things click. Based on his build and athleticism, they might.

Drafted: 11th Round, 2019 from Fresno State (SEA)
Age 21.9 Height 6′ 0″ Weight 200 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
30/40 55/55 25/45 45/45 40/50 60/60

Bins has plus bat speed and a great build for a catcher. His swing is grooved and he needs defensive polish, but he at least has power/arm carrying tools and a good chance to be a whiff-prone backup.

23. Ljay Newsome, RHP
Drafted: 26th Round, 2015 from Chopticon HS (MD) (SEA)
Age 23.4 Height 5′ 11″ Weight 210 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
50/55 45/45 55/60 55/60 89-92 / 94

Like Gerber, Newsome has a short, weird arm action that seems to bug hitters and create abnormally strong results on a fastball that is, in most respects, barely average. He does have a plus changeup and throws an obnoxious rate of strikes. To this point, Newsome’s smoke and mirrors have worked as a starter up through Hi-A. The velo bump he worked for two offseasons ago has made a difference, and he projects as a swingman type now.

Signed: July 2nd Period, 2017 from Dominican Republic (SEA)
Age 20.7 Height 6′ 2″ Weight 175 Bat / Thr R / R FV 40
Tool Grades (Present/Future)
Fastball Slider Cutter Command Sits/Tops
50/55 45/50 45/50 45/55 90-95 / 97

The Mariners pushed De Los Santos to full-season ball last year because his secondary stuff desparately needed reps and they trusted him to scrap through starts early on even though it wasn’t ready. He succeeded and now looks like a fastball/cutter/slider relief prospect.

35+ FV Prospects

25. Devin Sweet, RHP
Drafted: 0 Round, 2018 from North Carolina Central (SEA)
Age 23.5 Height 5′ 11″ Weight 185 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
50/50 45/45 55/60 50/55 90-93 / 95

Sweet was a 2018 undrafted free agent senior sign who had a 2019 breakout. He began the year in the Low-A bullpen (50 K, 9 BB in 35 innings), then in June was moved to the rotation and thrived for 12 starts. He made a few late-August starts at Hi-A, and was good there, too. Sweet has fastball command, fastball ride, and a plus changeup. He’s a little light on velocity, only sitting 90-93, but he’s garnered swings and misses at that velocity at the top of the strike zone so far. His changeup has bat-eluding sink and fade, and is used against righty hitters. The breaking ball is just okay, but he can land it for strikes to start counts.

It’s a 40-man look, to be sure. Perhaps the velo would tick up in the bullpen in an interesting way (all our Sweet info comes from folks who’ve seen him start), but for now he projects in the fifth or sixth starter area.

26. Yohan Ramirez, RHP
Signed: July 2nd Period, 2016 from Dominican Republic (HOU)
Age 24.9 Height 6′ 4″ Weight 190 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Curveball Command Sits/Tops
60/60 60/60 60/60 20/35 94-97 / 99

Ramirez’s career got off to a late start (he didn’t begin playing pro ball until he was 21) and he was also a little slow to develop, languishing in A-ball for several years. His stuff really started to pop in 2018, and last season he showed bat-missing, multi-inning stuff — 92-97, up to 99, two plus breaking balls. He walked 74 hitters in just over 100 innings last year, which needs to be better if he’s going to stick.

27. Jorge Benitez, LHP
Drafted: 9th Round, 2017 from Leadership Christian HS (PR) (SEA)
Age 20.8 Height 6′ 2″ Weight 155 Bat / Thr L / L FV 35+
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
45/50 45/55 40/50 35/45 88-93 / 94

Rejoice! Those who saw Benitez as an amateur and hoped he’d enjoy a pro velo bump have been proven correct, as the 20-year-old lefty was sitting 89-92 and up to 94 last year. He has big curveball spin rates but the pitch is pretty easy to identify out of his hand, and he barely throws it. It’ll be interesting to see if the dev group tries to make the curveball more playable or if they explore other out-getting avenues now that viable velo appears to be on the way.

Drafted: 11th Round, 2018 from Kings Way HS (WA) (SEA)
Age 20.7 Height 6′ 4″ Weight 225 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Curveball Command Sits/Tops
45/50 50/55 55/60 40/50 89-93 / 95

The fastball/frame projection here is just okay, but Casetta-Stubbs has two excellent breaking balls and an advanced understanding of how to deploy them together to thwart hitters, similar to how Drew Pomeranz attacks guys. He’s a black sheep relief prospect.

Drafted: 14th Round, 2018 from Houston (WSN)
Age 24.1 Height 6′ 0″ Weight 220 Bat / Thr L / L FV 35+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
50/50 50/50 50/50 35/35 90-93 / 94

Fletcher’s big hip turn helps him hide the ball pretty well, his slider has sufficient sweep despite low spin rates, and his changeup and two-seamer pair well together. He’d be a 40 FV relief prospect if his command were a shade better.

30. Raymond Kerr, LHP
(SEA)
Age 25.5 Height 6′ 3″ Weight 185 Bat / Thr L / L FV 35+
Tool Grades (Present/Future)
Fastball Slider Splitter Cutter Command Sits/Tops
60/65 40/45 50/60 40/50 30/40 94-98 / 100

Kerr can dunk a basketball, he has superlative weight room exploits, and he has rare lefty velo. His splitter flashes plus and the Mariners have worked with his slider enough to create viable sweep on the pitch. The strike-throwing and secondary consistency are present issues, but Kerr has come so far, so fast (he was sitting in the low-90s early last spring) that it’s fair to project on that stuff, even though he’s in his mid-20s.

31. Milkar Perez, 3B
Signed: July 2nd Period, 2018 from Nicaragua (SEA)
Age 18.4 Height 5′ 11″ Weight 173 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
25/55 45/50 20/45 40/30 40/50 50/55

Perez has more of a frame than his measurables suggest, he has advanced feel for the strike zone and for contact, and he might grow into enough power to profile as a well-rounded everyday third baseman. But the frame isn’t so overtly projectable as to make it a likelihood.

32. Kristian Cardozo, RHP
Signed: July 2nd Period, 2019 from Venezuela (SEA)
Age 17.4 Height 6′ 1″ Weight 175 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
40/50 45/50 40/50 30/50 null / 92

Cardozo signed for just shy of $600,000 last July. He doesn’t have the typical July 2 prospect’s physical projection, but his delivery is loose and repeatable. He’s been up to 92 with feel for his breaking ball and change.

Signed: July 2nd Period, 2013 from Dominican Republic (SEA)
Age 24.3 Height 6′ 1″ Weight 175 Bat / Thr L / L FV 35+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
30/35 50/50 35/40 60/60 50/50 60/60

He’s 24 but I still think Liberato’s physical tools and relatively solid track record of performance merit inclusion in this FV tier. He runs well, has a great frame, and made substantive improvements to his contact rates with a 2018 swing change. I think there’s still a chance he contributes in some way.

Drafted: 5th Round, 2019 from Florida International (SEA)
Age 22.2 Height 6′ 0″ Weight 205 Bat / Thr L / R FV 35+
Tool Grades (Present/Future)
Hit Raw Power Game Power Run Fielding Throw
30/45 55/55 30/50 30/30 40/45 50/50

Shenton had a loud Cape, then regressed athletically the following spring and looked more like a future first baseman. He has pop, but needs to hit a ton to profile at either corner spot.

35. Sam Carlson, RHP
Drafted: 2nd Round, 2017 from Burnsville HS (MN) (SEA)
Age 21.3 Height 6′ 4″ Weight 195 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Curveball Changeup Command Sits/Tops
55/60 45/50 50/60 40/55 89-93 / 94

We’re still collectively waiting for Carlson to pitch coming off of Tommy John. At his prep peak, he was into the mid-90s with a good changeup and more strikes than is typical for such a hard-throwing, cold-weather prospect.

36. Levi Stoudt, RHP
Drafted: 3rd Round, 2019 from Lehigh (SEA)
Age 22.3 Height 6′ 1″ Weight 175 Bat / Thr L / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Changeup Command Sits/Tops
45/50 40/45 50/60 40/45 90-92 / 94

Stoudt is a relief prospect with a plus changeup who went lower in the 2019 draft than his talent suggested because the industry knew he needed TJ after signing.

37. Ty Adcock, RHP
Drafted: 8th Round, 2019 from Elon (SEA)
Age 23.1 Height 6′ 0″ Weight 213 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Curveball Changeup Command Sits/Tops
65/65 45/50 40/50 45/50 30/35 94-97 / 100

Adcock is a catcher conversion arm who emerged a year after he was first draft-eligible. He’s an upper-90s power relief prospect who didn’t throw after the draft.

38. Jake Haberer, RHP
Drafted: 0 Round, 2018 from Eastern Illinois (SEA)
Age 25.1 Height 6′ 2″ Weight 225 Bat / Thr R / R FV 35+
Tool Grades (Present/Future)
Fastball Slider Sits/Tops
65/65 45/50 94-97 / 99

An undrafted free agent who was signed out of Indy ball with the notion that he’d eventually be an in-office contributor, Haberer cruised through A-Ball and now is in the upper levels at age 24 and throwing very hard. He was up to 99 last year and has a shot to be a bullpen contributor.

Other Prospects of Note

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

Arm Strength Relief Sorts
Yeury Tatiz, RHP
Dayeison Arias, RHP
Natanael Garabitos, LHP
Taylor Guilbeau, LHP

Tatiz almost made the main section of the list. He’s 19 and up to 95 with an average slider. Arias has performed as a pro, striking out 160 hitters in 116 pro frames. He’s consistently been in the 92-96 range as a lower-minors closer. He has an odd, swinging gate delivery that swivels about an axis created by a stiff front leg. If that’s not a long-term issue, then he’s a middle relief up/down type. Garabitos was up to 97 at age 18 but has little idea where it’s going right now. Guilbeau is in the mid-90s (it doesn’t play that way, though) with a good changeup and is on the big league roster fringe.

Bench Bats
Donnie Walton, SS
Dom Thompson-Williams, OF
Connor Hoover, INF

There’s not much upside from this group. Walton is a versatile 26th man possibility. DTW is now 24 and the late-blooming possibilities are gone. He’s a smaller-framed guy who is a fifth outfielder at best. Hoover was old for his level last year but his swing has some verve and he might be a bat-first infielder.

Older Depth Arms
Penn Murfee, RHP
Anthony Misiewicz, LHP
Kyle Wilcox, RHP
Darin Gillies, RHP
Scott Boches, RHP
Nick Duron, RHP
Collin Kober, RHP

This group is pretty self-explanatory. They’ll sit at the upper-levels and provide viable innings if a rash of injury occurs. Murfee and Misiewicz are pitchability arms. Murfee is the current minor leaguer most likely to be a GM based on what people in and out of the org say about his aptitude for learning and implantation. Wilcox and Gillies both throw pretty hard (up to 96/97) and performed at upper levels last year. Boches is a spin/ride mid-90s relief arm, Duron has more arm strength and is up to 97 but with fewer underlying traits to bolster it, and Kober is a heavy sinker submariner who has missed bats.

Young Sleeper Arms
Blake Townsend, LHP
Tim Elliott, RHP
Danny Chang, LHP

Townsend is a strong-bodied teenage Aussie up to 93 with a shot for an above-average slurve. Elliott has a plus curveball and fringe other pieces. Chang struck out a lot of AZL hitters with a spin-efficient fastball in the mid-80s but needs to get much stronger to develop viable big league velo.

System Overview

It’s clear the developmental changes on the pitching side have already begun to produce results in the form of the many older, 40-man-worthy arms on this list. The same is not yet true for the hitters. 50% of prospects on The Board are hitters, but they only comprise a third of this org’s list, and it’s an even lower ratio if we include the Others of Note. Several of the bats on the list are very good, though, and have responded well to aggressive assignments.

That’s not to say this org doesn’t still have some odd, developmental quirks. Out-of-place, early-season assignments for players like Deivy Florido (Triple-A, stuff dipped throughout the year and he didn’t make the cut here), Damon Casetta-Stubbs (Hi-A), Cesar Izturis Jr. (Triple-A, 2018), and Connor Hoover (Double-A), or mid-season, single-game promotions for Ray Kerr, Ljay Newsome and Colin Kober (all to Triple-A) look, to me, like ways of toying with opponents’ pro scouting models by indicating to the model that those players were promoted. The org’s explanation for my tinfoil hat theory is that the Mariners reward pitchers for hitting measurable goals and would like to get them acclimated to the idea of going up a level to pitch on short notice and then heading back down, both of which are pretty reasonable explanations.

We hoped you liked reading Top 38 Prospects: Seattle Mariners by Eric Longenhagen!

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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 ESPN.com. Previous work can also be found at Sports On Earth, CrashburnAlley and Prospect Insider.

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Metsox
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Metsox

Anything on George Feliz? Great list!