How Alex Bregman Signing With the Red Sox Could Impact the Mariners
Houston Astros third baseman Alex Bregman fields a ball during a game in 2017.
The Alex Bregman saga has finally reached its long awaited conclusion. First reported by The Athletic’s Chandler Rome on Wednesday night, Bregman and the Red Sox have agreed on a three-year, $120 million contract that includes deferred money and opt-outs after the 2025 and 2026 seasons.
There are a lot of ways to look at this from the Mariners’ perspective. First and foremost, while this outcome was expected, Bregman is now officially out of the American League West division after being a thorn in Seattle’s side for the past nine years as a member of the Astros. In 121 career games against the Mariners, Bregman has slashed .272/.345/.430 with 12 home runs, 27 doubles, and 54 runs driven in.
Bregman spurning the Cubs and Tigers likely makes widely speculated targets Nico Hoerner, Matt Vierling, and Jace Jung unavailable for the time being, but it instead may open the door to several potential trade opportunities with a Red Sox team the Mariners have reportedly had many conversations with over the course of this past offseason, most notably centered around Seattle right-handed starting pitcher Luis Castillo and Boston first baseman Triston Casas. There have been conflicting reports from both Boston and Seattle local media about the seriousness of those talks and the Mariners’ exact level of interest in Casas, with Seattle Times beat reporter Adam Jude most recently claiming the Mariners determined Casas was not an ideal fit for their ballpark. Other reports have indicated that Seattle does like Casas, but doesn’t value him as much as Boston. Jude, along with fellow Seattle Times reporter Ryan Divish, also reported that the Red Sox made two separate attempts to send Casas to the Pacific Northwest: once in the early stages of the offseason for one of Bryce Miller or Bryan Woo, and again later down the road with an offer that would have netted Boston Castillo but also required Seattle to take on the remaining three years and $55.8 million of outfielder/designated hitter Masataka Yoshida’s contract. The Mariners reportedly balked at both proposals.
The Red Sox moved on from their pursuits of Castillo and instead set their sights on former Dodgers pitcher Walker Buehler, who they signed to a one-year, $21 million contract. That seemed to effectively close off any path to a deal between Boston and Seattle, but Bregman’s decision may be the key to re-opening that line of communication, though Castillo nor Casas might be among the names discussed. The determining factor for such speculations will be how the Red Sox plan to deploy Bregman positionally. Rafael Devers has manned third base for Boston since 2017, but he’s coming off two dreadful seasons in which he was worth a combined -14 outs above average at the position, sparking the idea of a switch to first base, Casas’ current home. This would create a bit of a roster headache for the Red Sox as Casas, on paper, cannot simply slide into a primary designated hitter role due to the aforementioned $55.8 million man, Yoshida, who posted -8 outs above average in the outfield during his rookie season in 2023 and only appeared in one game in the outfield in 2024.
Could the Red Sox find a way to offload Yoshida before Opening Day? Perhaps, but even if Boston is willing to eat a portion of his salary, it’s hard to fathom many teams are looking to add a multi-year contract worth a significant chunk of change in mid February, particularly for a player who seemingly can only DH. The easiest path here for the Red Sox would be to have Bregman play second base, something Bregman’s agent, Scott Boras, has said his client is willing to do following elbow surgery in November. But from a pure defensive optimization standpoint, Boston would probably be better served running Bregman out at third and moving Devers to first.
As their uncharacteristically quiet offseason dragged out, it was reported by MLB.com writer Daniel Kramer that the Mariners were waiting for Bregman to make his decision in hopes that it would create a domino effect in the infield market that they could capitalize on. But as the days went by and Bregman remained unsigned, Seattle decided to wait no longer and reunited with Jorge Polanco on an incentive-laden one-year, $7 million contract and named the 11-year veteran its starting third baseman. That has left president of baseball operations Jerry Dipoto and general manager Justin Hollander with roughly $4-5 million left of the highly restrictive, reportedly $16 million budget placed upon them by Seattle’s ownership group.
If Bregman’s arrival in Boston does make Casas more available via trade, he would still make sense for Seattle both from a roster and financial standpoint. Casas is still a year away from becoming arbitration-eligible, meaning he’s making the league minimum salary of $800,000 in 2025, and could easily slot in at first base for the Mariners, pushing Luke Raley back into his previous role as one of the team’s four rotating outfielders and DH options. But that presents a major question, and one the Mariners may not have the answer to: what would it cost? The Red Sox likely have little-to-no interest left in Castillo after adding Buehler and Garrett Crochet to a group of starting pitchers that also includes Brayan Bello, Kutter Crawford, Tanner Houck, Lucas Giolito, Richard Fitts, Cooper Criswell, Hunter Dobbins, and Quinn Priester. But even if they were interested, Seattle would then be left to either significantly downgrade in its rotation by going from Castillo to Emerson Hancock, roll with an unproven starter such as Logan Evans, or scramble to find a replacement for Castillo within a Casas-Castillo swap, which further complicates a potential deal, or elsewhere on the market with very limited funds and only six weeks to go before Opening Day.
Despite their well-documented deficiencies, the Mariners still possess one of the more talented rosters in the game, but they lack the depth and willingness to spend that would allow them to feasibly survive trading from a different area of their major-league roster, especially with the regular season right around the corner. That may be the only area of the Mariners’ organization the Red Sox have interest in when it comes to trading Casas, however, meaning a pure prospect return from Seattle is unlikely to push something across the finish line. Thus, the odds that Casas dons the navy and Northwest green within the next few weeks appear minuscule at best.
That said, the addition of Bregman could make the Red Sox more willing to move one of their part-time infielders, such as David Hamilton or Vaughn Grissom. The latter would likely be the most exciting of the two options for fans, as Grissom has long carried a great amount of hype around him, dating back to his days within the Braves organization, but has thus far seen his major-league career stunted by injuries and poor performance. Nevertheless, Grissom is only 24 years old, has a minor-league option left, and added 20 pounds of muscle over the course of the offseason, per Red Sox chief baseball officer Craig Breslow. He also plays a position of uncertainty for the Mariners at the moment: second base, where longtime utility man Dylan Moore is currently slated to play every day with Ryan Bliss mixing in on occasion until top prospect Cole Young is deemed ready for his first taste of the majors. Hamilton would also be a fit for similar reasons, though the Mariners may view him as more of an option to backfill Moore’s previous role. The cost and availability of either player is undetermined, but it would seem reasonable to think prospect capital and/or mid-leverage relief talent could get something done.
After the signing of Polanco, both Hollander and Dipoto have alluded that Seattle’s roster in its current state will look the same once Opening Day rolls around on March 27, but both executives have also left the door cracked open for the possibility of further additions. While it may not be for Casas, perhaps Bregman, the man the Mariners spent a decent chunk of the offseason waiting on, has allowed the stars to align for one more move.
