I’ve never viewed myself as a Miles Mastrobuoni truther. With all due respect, I’m not sure that many people have. If I started this article by asking if we’re underappreciating Miles Mastrobuoni, I don’t even know if you’d keep reading. The majority of his plate appearances, on the surface, seem to back up these claims. But, I think it’s time to take a closer look at his impact on last year’s Mariners team.
Mastrobuoni was traded to the Mariners from the Chicago Cubs one year ago yesterday, in exchange
for cash considerations. With the Cubs, he played in 111 games across two seasons, and was used primarily as both a shortstop and third baseman. The Mariners picked up Mastrobuoni to add another utility bat to the lineup ahead of the 2025 season, or as John noted last year, to increase the number of Italians on their roster.
The circumstances in which Mastrobuoni enters a game are some of the toughest to produce quality at-bats. He is called upon in high-leverage situations to make a positive impact on the play at hand, or to start in the absence of an everyday player. As the true definition of a utility player, Mastrobuoni played the following positions last season: first base, second base, third base, left field, right field, designated hitter, and once as relief pitcher (it was an off-putting summer afternoon in Minnesota, don’t ask). Throughout the season, he frequently assumed the role of starter, pinch hitter, and pinch runner, and bounced between the major league roster and Triple-A Tacoma to fit the needs of each team.
In 175 major league plate appearances during the 2025 regular season, Mastrobuoni slashed .250/.324/.296 and carried a 16.6% strikeout rate. According to FanGraphs, his on-base percentage was slightly above league average, and his strikeout rate significantly below league average. With a 16.1% whiff rate and 19.2% chase rate that rank in the league’s upper percentiles according to Statcast, his plate discipline has been proven by his ability to select pitches in the zone and make solid contact. Meaning, as a player whose sole job it is to get on base, Mastrobuoni has exceeded expectations. He is no superstar by any means, but he is doing what the team asks of him, and that is all we as fans can hope for.
The effectiveness of his 2025 numbers might come as a surprise, but he was as consistent as it gets at the plate throughout the year. Mastrobuoni comparatively slashed .296/.415/.417 with a 12.7% strikeout rate in Triple-A across 142 total plate appearances, and made many trips back and forth between Tacoma and Seattle. In his limited opportunities, he was able to regularly translate his minor league numbers to the major league level. In fact, Mastrobuoni was one of the most productive pinch hitters in the entire league through the halfway mark, as mentioned by Kate back in July (Donovan Solano jump scare warning).
Defensively, Mastrobuoni provided a similar sense of stability. His Outs Above Average (OAA) through all field positions he played in 2025 ranged from 0 to 1, and he carries a career Defensive Runs Saved (DRS) of 2. Thus, his numbers show that he is at least providing an average defensive performance at each position he rotates through. Plus, his versatility has shown through highlight-reel plays at multiple different positions.
With the Mariners’ veteran utility player Dylan Moore picked up by the Texas Rangers in August, Mastrobuoni is primed to be the team’s go-to in 2026. He will likely share some at-bats and pinch running duties with Leo Rivas, while still holding the majority of major league appearances. With as challenging of a role as he has assumed, both Mastrobuoni’s offensive and defensive appearances frequently accomplished what was asked of him. He posted many career-best numbers in 2025, and his upcoming goals should remain the same as last season: turn every opportunity into a positive impact on the team.
