Mariners Bolster Lineup by Acquiring Josh Naylor From Diamondbacks
The deafening quiet of this year’s July trade market was disturbed on Thursday night with the announcement that the Seattle Mariners were acquiring first baseman Josh Naylor from the Arizona Diamondbacks. Naylor has provided more than respectable offense for the Snakes this year, hitting .292/.360/.447 with 11 homers, good for a 123 wRC+ and 1.4 WAR. Heading to the desert in return are two minor league pitchers, lefty Brandyn Garcia and righty Ashton Izzi.
While the Diamondbacks have generally disappointed in 2025, little of the fault can be placed at Naylor’s feet. The team expected to compete in 2025, but lost Christian Walker to the Astros in free agency, so the hope was that Naylor would fill the hole for a year before hitting the open market himself. He was never going to be an elite defensive first baseman like Walker, but the expectation was that he would at least provide a similar level of offense. Naylor is likely to fall well short of his career-high 31 homers from 2024, but he’s compensated for that by adding nearly 50 points of batting average, meaning his 123 wRC+ is actually slightly higher than his 119 mark from last season.
If the season ended today, the Mariners would make the playoffs as the second AL Wild Card, and the five-game separation between them and the division-leading Astros is not an insurmountable distance. Houston’s edge in the AL West seems even smaller when you consider how much of its lineup is currently out hurt. The injured quartet of Yordan Alvarez, Isaac Paredes, Jeremy Peña, and Jake Meyers would represent a huge chunk of any team’s offensive value. First base has been a particular source of trouble for the M’s this year, with their first basemen ranking in the bottom third in baseball with a combined 0.4 WAR. The original plan had been for Luke Raley to get the lion’s share of the playing time at first, mostly against righties, with fill-ins around him to take care of the southpaws. However, injuries to Mitch Haniger and Victor Robles thinned out Seattle’s corner outfield and DH depth and pushed Raley mostly to right field. As a result, the team was forced to give a lot of playing time to Rowdy Tellez; he posted an execrable .249 on-base percentage with the Mariners before they dropped him in June.
Naylor is not a superstar, so naturally, his acquisition doesn’t dramatically change the face of the AL West race. After last night’s win over the Angels, ZiPS gave the Mariners a 76% chance to make the playoffs and a 24% probability to win the division. These numbers would be 72% and 21% without the trade.
So, what’s the cost for their new first baseman? Neither Garcia, nor Izzi was torching up the prospect lists, but then again, Naylor is a free agent after the season, making this trade is a pure short-term rental. The 25-year-old Garcia has already made a brief major league debut, and since I don’t believe the Diamondbacks are going to go full rebuild, that has a lot of allure over the compensation draft pick they would have gotten if they’d held onto Naylor and he’d signed elsewhere this offseason. Garcia is a hard-throwing lefty sinkerballer with a three-quarters delivery who predictably induces a lot of grounders. My colleague Eric Longenhagen gave him a 40+ FV when Seattle’s top prospects list was published last month.
The ZiPS projections see Garcia as a solid, though unspectacular, mid-bullpen arm with at least some upside.
| Year | W | L | ERA | G | GS | IP | H | ER | HR | BB | SO | ERA+ | WAR |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | 3 | 3 | 4.22 | 57 | 0 | 53.3 | 48 | 25 | 5 | 22 | 45 | 98 | 0.0 |
| 2027 | 3 | 3 | 4.10 | 56 | 0 | 52.7 | 47 | 24 | 5 | 21 | 45 | 101 | 0.1 |
| 2028 | 3 | 2 | 4.08 | 55 | 0 | 53.0 | 46 | 24 | 4 | 21 | 45 | 102 | 0.2 |
| 2029 | 3 | 2 | 3.92 | 46 | 0 | 43.7 | 39 | 19 | 4 | 17 | 37 | 106 | 0.1 |
| 2030 | 2 | 2 | 4.06 | 40 | 0 | 37.7 | 33 | 17 | 3 | 15 | 32 | 102 | 0.1 |
| 2031 | 2 | 1 | 4.06 | 33 | 0 | 31.0 | 27 | 14 | 2 | 12 | 26 | 102 | 0.1 |
| Percentile | ERA+ | ERA | WAR |
|---|---|---|---|
| 95% | 128 | 3.23 | 0.7 |
| 90% | 122 | 3.40 | 0.6 |
| 80% | 114 | 3.65 | 0.4 |
| 70% | 107 | 3.88 | 0.2 |
| 60% | 102 | 4.06 | 0.2 |
| 50% | 98 | 4.22 | 0.0 |
| 40% | 93 | 4.43 | -0.1 |
| 30% | 90 | 4.59 | -0.2 |
| 20% | 86 | 4.83 | -0.3 |
| 10% | 77 | 5.36 | -0.6 |
| 5% | 71 | 5.82 | -0.9 |
As a 21-year-old in High-A ball, Ashton Izzi has more developing to do than Garcia, but even with decidedly mixed results, the righty showed enough upside for Eric to also give him a 40+ FV. According to Eric, Izzi boasts a four-seamer that sits around 94 mph with solid movement. He gets “near elite” extension with his fastball, but it doesn’t generate many whiffs. Izzi also has a usefully average two-seamer, Eric says, as well as a sweeper and a cutter; the sweeper is a big swing-and-miss pitch for him. His changeup is mediocre, and Eric is concerned that Izzi will struggle to develop a good weapon to wield against lefties. Overall, per Eric, if Izzi can clear his developmental hurdles, he can make the majors as a starter.
In all, I think getting two real prospects, one who can impact the parent club immediately, is an absolutely fair return for Naylor. The Mariners have only two playoff wins over the last two decades, and now is the time to go all-in to add to that total. Their offense is better this season than in previous years, but they still needed to fill their hole at first base, and Naylor represents a major upgrade over what they had before.
Dan Szymborski is a senior writer for FanGraphs and the developer of the ZiPS projection system. He was a writer for ESPN.com from 2010-2018, a regular guest on a number of radio shows and podcasts, and a voting BBWAA member. He also maintains a terrible Twitter account at @DSzymborski.
First things first: Dipoto often loses his deals with the D-Backs. They traded away Ketel Marte (and Taijuan Walker) for Jean Segura and Mitch Haniger, a deal that looked like a huge win for the Mariners at first and now looks really different after Marte turned into a high-end star and Haniger was wrecked by injuries. He then dumped Eugenio Suarez for Seby Zavala and Carlos Vargas, which ended badly enough that the Mariners are now desperately trying to re-acquire him. The Sewald for Rojas deal is probably a wash, Rojas was better but still frustrating enough that he got non-tendered.
But I have a very hard time being down on this deal for the Mariners. Getting a guy with a 123 wRC+ for the stretch run to bolster a lineup for a probable middle reliever and a vaguely interesting guy pitching in high-A? If this is what it costs to acquire help, I am not sure I would be selling right now if I were the D-Backs or other teams on the bubble. The Orioles are probably cursing Mike Hazen for making this deal as I type this. And I type this with the full knowledge that history suggests Dipoto is going to regret trading one of those two guys away.
And now I’m seeing that the Rockies basically dumped McMahon’s contract on the Yankees who didn’t even merit a writeup on Eric’s prospects list, which went 45 graded prospects deep and then something like another 30 prospects of note after that? I mean, I know McMahon isn’t worth much at all but there are so many buyers and so few sellers, you would think someone would have offered actual prospects.
I’m not 100% sure that McMahon is really an upgrade on DJ LeMahieu. He likely be a more capable fielder but he’s probably a worse hitter. Of the nine season McMahon has been in the majors, he’s only finished one (2024) with a higher wRC+ than LeMahieu. DJ was cut this year, with a better park-adjusted batting line than McMahon.
The NYYs are on the hook for $36M in future payroll, and gave up two decent AA-performing non-prospects for the ability to move Jazz over to 2nd base.
Yeah, the contract was probably the rub for McMahon, it’s a decent chunk of change over 2+ years for an underperforming 30-year-old 3rd baseman.
Better late than never for the Rockies, I guess. I was a little surprised to see this move as I thought McMahon was a certified Rockies Guy™ who wouldn’t be traded.
I think that we can add this to the list of Rockies missteps. One of their biggest problems is that since Brdich left they never want to trade a player when they’re playing well, only when they are playing poorly. Which means they are always selling low.
This has happened several deadlines in a row where they have rebuffed interest in players who are doing well, and the next year they’re excited about trading them after their value has been destroyed. The one that stood out to me was Jake Bird, maybe because it’s one of the more recent ones. He had a fantastic 2023, and the Rockies said he was off limits. Then he crashed in 2024, and the Rockies wanted to trade him. Now he’s better than ever. Will the Rockies trade him? Probably not.
In any case, McMahon had a 109 wRC+ in the first half last year and the Rockies were terrible. Instead, they kept McMahon because he was a “favorite” of Dick Monfort. Funny how he’s not a favorite anymore when he stops hitting? So instead of getting actual value back they’re just dumping his salary.
Totally agreed. They seem to have absolutely no sense of where their organization is at, at any point. There is not much wisdom in keeping decent performers around when they are aging/expensive and you haven’t won more than 70 games in a season since 2021.
Thank them for their service, get the best return you can, and look toward the future.
They do have pretty good luck with former Rockies infielders, at least at first.
I think LeMahieu probably isn’t as done as he looked last year, but for whatever reason they weren’t interested in giving him a starting job anymore and LeMahieu didn’t seem too interested in being a backup.
LeMahieu said that he basically didn’t feel like he could physically play third anymore. There is a stark difference defensively between the Jazz at 2B, anyone else at 3B versus the LeMahieu at 2B, Jazz at 3B alignment.
While it could have been worse, giving up anything of remote value for McMahon feels like an overpay.
I think Rocky hitters need to be examined more. Going on the road from Coors is likely as big of a hindrance as hitting at home is a positive. It’s so hard to hit at sea level after being a mile high.
That NYY settled for McMahon suggests ARI is asking a lot for Suarez.
The M’s also got Canzone (and Ryan Bliss) in the Sewald trade. That one is an unqualified win.
Agreed, Sewald’s been basically replacement level since the trade. You can argue he would have been better if he’d stayed in Seattle and helped them down the stretch in 2023/24, but their second base situation was terrible in 2023 before Rojas stabilized it a bit down the stretch and he was solidly fine in 2024 (if frustrating), and that’s not factoring in that Canzone is performing well right now and looks at least like he can be a strong-side platoon bat, and that’s not even factoring in that Bliss still has a non-zero possibility of being something useful.
It wasn’t a heist, but making the trade was at worst net-neutral to the 2023-24 Mariners (depending on how well you think Sewald might have performed if they kept him), Rojas’s contributions might have even made them a little better than Sewald would have, and undoubtedly they’re better for it right now.
I think it’s a pretty clear win for the DBacks if Izzi can even be an acceptable 4/5 starter for a few years and Garcia is a helpful bullpen piece. Neither may happen, but the DBacks probably think it can.
Mariners got two good years from Segura and flipped him for J.P. Crawford, which makes that deal look better, though they’d certainly like to have Marte back.
The other thing is, they wouldn’t necessarily have Marte now if they had kept him. If you compare the WAR for Marte+Walker vs. Segura + Haniger pre free agency, it’s actually about the same, without even adding in JP Crawford. Casting that as a fail for the Mariners is always weird to me.
I feel like we always overvalue rentals. Half season of a okay ~2.5 war 1b was probably not going to get a good prospect. Just from pure value standpoint, it’s like, ~3-5 min of surplus value which is like filler prospect territory
Sometimes teams overpay for pitching rentals bc they are more important for playoffs, but when was the last time we really saw an overpay for a rental? In hindsight the Ragans trade was bad but at the time he was like a 45 FV
I agree with the statement as written, although I would put it a slightly different way. Position players help you win the regular season, pitching helps you win the playoffs. But right now there are a truly amazing nine teams with playoff odds above 89%.
What’s more confusing to me in this case, as I look at it, is that the next five teams in the playoff odds need a first baseman or DH. The Mariners are the ones who traded for him and are probably the ones who need him the least (79.5%), but then we have the Red Sox (43%), Padres (42.9%), Giants (39.9%), and Rangers (31.7%). It’s hard to trade within the division, so I sort of get that, and the Rangers are on the border of buying and selling, and maybe the D-Backs really just wanted pitchers and most of the pitching prospects they have at 40+ and 45 are in the low minors…IDK.
I don’t think league-average first basemen on expiring contracts get more of a return than this anymore. Gone are the days of getting a high ranked prospect for 60 games of a good hitter’s services. I strongly doubt the D-backs would have gotten a better return by waiting.
Not responding to the Dipoto bits, that’s just internet argument bait.
You don’t want to argue on the internet?! What are you even doing here?!
When your below average an average or slightly above average player looks like a giant.
Vargas has been a high leverage reliever for Seattle (1.65 pLI) and carried a 3 ERA into July. Has given up 7 ER in last 6 games though, knocking him below replacement level. Will be interesting to see how he does going forward.