Mariners 2025 Trade Deadline Guide

40 player profiles, all complete with cost and fit analysis. My 2025 Mariners Trade Deadline Guide is here!

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Ryan O’Hearn

Ryan O’Hearn is essentially a near-perfect fit for what Seattle needs at this deadline. The Mariners preferably need a left-handed first baseman who can immediately slot into the middle of their order. O’Hearn absolutely bangs, posting a .302/.383/.486 slash with a 149 wRC+. His only flaw is that he doesn’t hit left-handed pitching, but you can pretty easily plug him in at first base with Donovan Solano and feel great about that platoon. His 164 wRC+ against righties will absolutely play in the middle of this order. O’Hearn plays the outfield and first base, wouldn’t be expensive, and could immediately plug in.

The Orioles are no doubt sellers at the upcoming deadline, and O’Hearn on an expiring deal is as much of a lock as exists at this deadline. He shouldn’t cost a ton, and can patch up a massive position of need for the rest of 2025.

Trade Fit: HIGH

Trade Cost: Low/Medium

Cedric Mullins

O’Hearn’s teammate could also be a good fit on this roster, outfielder Cedric Mullins. Mullins is slashing .229/.312/.452 with a 118 wRC+. While his strikeout rate is a career high 25%, the SLG has returned and helped him rejuvenate himself this season. Mullins has hit lefties and righties well this season, although in relatively limited exposure to left-handed pitching. His splits have actually been reverse so far in 2025.

The only issue with acquiring Mullins is that you would have to play him in right field primarily, meaning that Luke Raley would be the first baseman. This is something Seattle has been reluctant to do on a more full time basis. I’m not sure this is a great fit, although I’ve been a fan of his for a long time. He will be a rental, and almost certainly will be dealt at the deadline.

Trade Fit: Medium

Trade Cost: Low/Medium

Yandy Diaz and Brandon Lowe

This is a tough one for me. On one hand, the Rays and the Mariners are a match made in heaven when a deal needs to get done. On the other hand, the Rays are in a much better position to grab a playoff spot as things currently stand. There have also been rumblings that Diaz and Arozarena do not get along.

With Cole Young in the fold, second base has become less of a need, although Lowe could play first or be a candidate to move to third. Lowe is having a great season and I would be interested in adding him to this roster, but his track record of health scares me and combining that with a position change is a tricky proposition.

Yandy Diaz has always been a tremendous fit in Seattle, but there are too many non-baseball questions here that ruin it for me. The Rays ask for the 33-year-old has always been astronomical, and the questions of his clubhouse fit remain an issue. While his profile would fit perfectly in this lineup, I think Seattle will go with one of the many cheaper, very comparable options out there on the market.

Overall, I would be happy with either of these players being added to Seattle’s roster, but I see a lot of roadblocks.

Trade Fit: Medium/Low

Cost: High