The Mariners' infield is set to undergo significant changes with the re-signing of Josh Naylor and the acquisition of Brendan Donovan. These moves address the need for a solid infield, with the loss of Jorge Polanco and Eugenio Suárez to free agency. Naylor and J.P. Crawford are locked into first base and shortstop, respectively, while Donovan will be an everyday player, providing solid defense at second base and the corner outfield. Ryan Divish of The Seattle Times notes that Donovan's early work with infield coach Perry Hill has focused on third base, a position he hasn't played since 2024, despite logging 269 2/3 innings there between 2022-24. His defensive grades are above-average, according to Defensive Runs Saved and Outs Above Average.
The infield depth is further bolstered by the presence of 20-year-old shortstop Colt Emerson, a top 10 overall prospect according to Baseball America, The Athletic, ESPN, and MLB Pipeline. Emerson had a strong season in the minors, combining a .285/.383/.458 batting line with 16 homers and 14 steals over 600 plate appearances across three minor league levels. He spent the majority of the season in High-A but impressed in Double-A, earning a late-season cameo at Triple-A Tacoma. Emerson's well-rounded skillset and maturity have earned praise from president of baseball operations Jerry Dipoto, who acknowledges the possibility of him earning a spot on the team.
The probable Opening Day infield lineup includes Naylor, Young, Crawford, and Donovan from right to left. Emerson could get consistent reps against Triple-A pitching while building experience at third base, where he has 111 1/3 innings of professional experience. He is the heir apparent at shortstop when Crawford hits free agency next winter but is unlikely to push the veteran off the position this year. If Emerson has a strong Spring Training, Donovan could return to second base, potentially moving Young to Triple-A.
The infield depth is further complicated by the presence of Ryan Bliss, a former second-round pick who hit .269/.377/.456 with 12 homers and 50 stolen bases in Triple-A in 2024. Bliss ruptured his left biceps on a swing two weeks into the regular season and underwent surgery, requiring a 4-5 month rehab timeline. He returned to minor league game action in September and had an impressive week in Triple-A. However, a meniscus tear in his right knee required season-ending surgery, and he is now back to full health this spring.
The Mariners' infield is set to become even more crowded with the potential promotion of Emerson. Bliss has a couple of minor league options remaining, and Leo Rivas also has an option, although he reached base at a .387 clip in 111 plate appearances last season and made the team's playoff rosters. Both Mastrobuoni and Luke Raley are out of options, and it's difficult to see Seattle carrying both players into the season if all hitters get through camp healthy. They will need bench spots for backup catcher Andrew Knizner and righty platoon bat Rob Refsnyder. Keeping Mastrobuoni and Raley would require them to option both Bliss and Rivas before considering an Emerson promotion, and Dipoto acknowledges the likelihood of uncomfortable short-term decisions.
