A significant first base target came off the board only a few weeks after free agency opened, a notable change from recent years when the market often dragged well into spring training.
The Seattle Mariners have reached an agreement to reunite with first baseman on a five year contract, first reported by MLB insider Jeff Passan on November 16. Ari Alexander of WHDH 7News noted that the deal is expected to fall in the ninety to one hundred million dollar range, though the exact terms have not yet been confirmed.
Seattle acquired Josh Naylor from the Arizona Diamondbacks at the 2025 trade deadline, and he proved to be an ideal addition during their postseason push. In 54 regular season games with the Mariners, Naylor produced a .299/.341/.490 line and an .831 OPS. Across the full season, he recorded 29 doubles, 20 home runs, and 30 stolen bases.
The Boston Red Sox have reportedly explored ways to strengthen first base, and Naylor stood out as one of the better options in this free agent class. Still, Boston was not connected to him as frequently as it has been to Pete Alonso, and there is good reason for that difference.
The Mariners reunion with Josh Naylor is good for the Red Sox, despite his abilities at first base
The Red Sox are searching for a significant power boost in their batting order. While Naylor’s 20 home runs would certainly provide some help, the team needs a more substantial surge. Boston lost 35 homers after dealing Rafael Devers to the San Francisco Giants last year, and they must account for that missing thump. Alonso hit 38 home runs last season, and Cody Bellinger, who can also handle first base, finished with 29. If Triston Casas returns strongly from his knee injury, he could potentially surpass 20 homers over a full season, although he has never achieved that mark in the majors.
Naylor also does not use the left field side of the ballpark often, which means he would not take full advantage of Fenway Park’s Green Monster. Alonso, a right handed hitter, would bring more balance to the lineup, and the Monster would suit his approach well, even though he is capable of hitting the ball out to all fields.
Seattle’s decision to bring Naylor back may also remove them from other free agent pursuits that could have affected the Red Sox. The Mariners had been seen as a possible destination for Alonso if Naylor had left. With Naylor returning, Boston now faces less competition in the former Mets slugger’s market.
Seattle is also searching for a third baseman after trading for Eugenio Suarez, an impending free agent, at the deadline to cover third during their playoff chase. Because the Mariners are not typically heavy spenders, Naylor’s contract could reduce their willingness to commit major money to someone like Alex Bregman or Suarez. That scenario could benefit the Red Sox if Bregman signs elsewhere and Suarez becomes a fallback option.
Naylor is a high quality first baseman who clearly meshed well with Seattle during the latter half of the 2025 season and into October, but his fit with Boston was always uncertain. With his return to the Mariners finalized, the Red Sox may now face a more favorable landscape in both corner infield markets.