Trade deadline primer: what should be the Mariners' priorities?

The Mariners will already be bringing first baseman Josh Naylor into the fold. What else do they have to add before Thursday?

Author

James Johnston
July 25, 2025

The Seattle Mariners knocked down the first domino of the 2025 MLB trade deadline on Thursday, trading for Diamondbacks first baseman Josh Naylor in a deal that sends pitchers Brandyn Garcia and Ashton Izzi to Arizona.

Naylor, who hit a walk-off grand slam against the Mariners at Chase Field earlier this season, fills a massive need at a position that has been covered by platoons involving Donovan Solano, Luke Raley and Rowdy Tellez for the entire year to this point.

The Mariners have struggled to find production against lefties as a whole so far this year, but particularly at the first base position. Solano has been the primary owner of the first base platoon role against lefties, but has not thrived in that role so far this year. The 37-year-old signed as a free agent by the Mariners this offseason has not hit well against lefties so far this year, producing a 27 wRC+ in that split.

Naylor is likely to be the everyday first baseman from here on out in 2025 before becoming a free agent at the end of the season. While only putting up an 82 wRC+ against lefties himself, this is still big improvement and provides much-needed stability in at the position.

A corresponding move has not yet been announced by the Mariners, though Naylor is expected to join the team in Anaheim tonight, so that announcement is imminent.

Solano and Dylan Moore are both out of options, so either player would need to be designated for assignment to be removed from the active roster. Miles Mastrobuoni and Dominic Canzone, on the other hand, both have available options, though one could probably say both have been more consistent producers than Solano and Moore to this point.

The Mariners’ decision on the corresponding move this afternoon could tip us off a bit on what direction they plan to head in the coming days before the deadline.

Compass Points: Ranking the Mariners deadline needs after the Naylor trade

  1. Relief pitching — With first base now out of the way for the Mariners, adding a mid-to-high-leverage reliever absolutely needs to happen before next week. The back end of the Mariners’ bullpen has been extremely reliable due to the contributions of Andrés Muñoz, Matt Brash, Gabe Speier and even Eduard Bazardo. However, it’s been the innings before the seventh, eighth, and ninth that has been causing issues for the Mariners. Blown leads, particularly in the middle innings, have been frequent for the Mariners this year.

    With injuries still impacting the rotation and the Mariners playing it safe on the innings workload, an additional reliable reliever out of the bullpen will help narrow that gap in innings. Adding a reliever like Griffin Jax (Twins) or Pete Fairbanks (Rays) could work wonders, allowing the Mariners to more appropriately distribute higher-leverage innings to stay in games and protect leads.

  2. Third baseman — This is a close second after relief pitching. Now, before everyone gets mad at me for saying this: Ben Williamson has done a damn good job with the situation he has been thrown into by the team this season. His defense at the corner infield spot has been solid for the Mariners so far this year. While he hasn’t been particularly good at the plate, with an 82 wRC+ on the season, he has managed to prevent the position from being a total black hole in the lineup.

    All this said, a team looking to contend for a World Series (which the Mariners say they are) needs to have a higher standard than “not a black hole” at one of their positions. An upgrade at the deadline is necessary. Judging by the reasonable price it took to acquire Naylor, plus the abundance of available third basemen on the market, the Mariners should be able to improve at the position without depleting their rich farm system.

    Maybe the most sought-after bat on the market this deadline is Diamondbacks third baseman Eugenio Suárez, whom the Mariners traded to Arizona after the 2023 season. The Mariners could potentially look to reunite with Suárez, especially with one of his biggest suitors — the Yankees — choosing to acquire Ryan McMahon from the Rockies earlier today. Yoan Moncada could also be an option, although Jerry Dipoto still has yet to make a trade with the Angels since being hired by the Mariners.

  3. Starting pitcher — This would just be a cherry on top. Adding a depth starter could provide a safety net for the Mariners in the final two months of the regular season. With three different starters missing time this season, Bryce Miller still on the injured list and Logan Evans still trying to find consistent footing at the Major League level, the Mariners could really use the insurance policy down the stretch. However, this is a move that should only be done for a reasonable price. The Mariners should be most aggressive in their pursuit to add to the bullpen and at third base.

    If the Mariners wanted to try to kill two birds with one stone, they could look to acquired either Merrill Kelly or Zac Gallen from the Diamondbacks in a package that also includes Suárez.

AL West & Wild Card Standings

The Mariners won the first game of a four-game set in Anaheim last night. Since last week, they have moved up into the second wild card spot in the American League.

Despite a ton of injuries, the Astros are managing to stay afloat atop the AL West, holding a five-game lead over the Mariners. The Rangers appear to be heating up as well, finally getting over the .500 hump in the last week. The Mariners will host the Rangers in Seattle next week for four games, beginning on Thursday.

Latest Transactions & Roster Moves

  • July 24: 1B Josh Naylor acquired from the Arizona Diamondbacks in exchange for LHP Brandyn Garcia and RHP Ashton Izzi.

  • July 24: RHP Jackson Kowar recalled from Triple-A Tacoma. LHP Brandyn Garcia optioned to Triple-A Tacoma.

  • July 21: LHP Brandyn Garcia selected from Triple-A Tacoma. RHP Juan Burgos optioned to Triple-A Tacoma.

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