According to Adam Jude of the Seattle Times, the Seattle Mariners are set to make a major change with top prospect Michael Arroyo: They are going to start transitioning him to left field.

Per Jude:

Interestingly, another top prospect, Michael Arroyo, will begin a transition from second base to left field during the Colombian Winter League season this month. Arroyo, 21, played second base exclusively in the minor leagues this year, but because of the Mariners’ quality depth on the infield, the club projects Arroyo as a left fielder long-term, and he could push for a major-league promotion at some point in 2026.

The Arroyo file

Rated as the No. 63 prospect in baseball, per MLB Pipeline, Arroyo spent 65 games with High-A Everett in 2025 before playing 56 games at Double-A Arkansas. A right-handed hitter, he hit .262 with a .401 on-base percentage across both levels, popping 17 home runs with 54 RBIs. He had just two home runs at Double-A, though Arkansas is a much more difficult environment for hitters.

He is not regarded as a strong defender at second base, which plays into the calculus of moving him to left field.

Listed at just 5-feet-10 inches, Arroyo wouldn't be a particularly big outfielder, but his bat is his calling card.

Why else this could make sense

The Mariners have an overflow of infielders, and are at a deficit in the outfield.

At the moment, Seattle has Cole Young, Colt Emerson and Ben Williamson, with all three knocking on the door of major playing time. Further behind, but coming, is top prospect Felnin Celesten. 

In the outfield? While Julio Rodriguez is locked in, Randy Arozarena and Victor Robles are both free agents after 2026. Is it possible that the 2027 outfield consists of Rodriguez, Arroyo and Lazaro Montes, another Top 100 prospect? 

Interesting to note

Arroyo is expected to be a major part of Colombia's World Baseball Classic team in 2026. Are they going to play him in left field also? Or, are they going to play him at second base, which will somewhat impact his spring training and development with the Mariners? It will be something to watch for as spring training and the WBC roll around.

The World Baseball Classic begins in early March and several Mariners are expected to participate.

Furthermore, because of the infield surplus, Arroyo's name has been mentioned in trade talks. Does the M's commitment to giving him growth in the outfield mean they are more likely to hold onto him? We'll have to wait and see.

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