Who is Marcelo Mayer? Why Red Sox are finally calling up Boston's No. 2 prospect to big leagues

The Red Sox have gotten off to a mediocre start to the season, but Boston is adding reinforcements from its stacked farm system.

After Alex Bregman suffered a right quad injury during Friday's game against the Orioles, the Red Sox have decided to call up prospect Marcelo Mayer, ESPN's Jeff Passan reported.

Mayer is the second-ranked prospect in Boston's system and is considered a top-10 prospect in all of baseball.

Bregman has been off to a strong start to his first season in Boston, but is expected to miss some time with the injury. According to manager Alex Cora, Bregman said the injury is "worse" than initially thought, which opens up a spot in the Red Sox infield.

Entering the year, the Red Sox had a slew of prospects from their strong farm system making a case for the big league squad, as Kristian Campbell broke camp with the team and Roman Anthony, the top prospect in baseball, is currently tearing up AAA. Mayer is now the second of the three to get the call to the majors, with Anthony seemingly not far behind.

Here's what you need to know about Mayer ahead of his MLB debut.

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Marcelo Mayer draft

Mayer was the fourth overall pick in the 2021 MLB draft out of high school and was arguably the best prospect in the class entering the draft.

MLB Pipeline was one of many outlets that had Mayer ranked No. 1 in the class, while ESPN had the shortstop ranked as the No. 2 player.

2021 MLB Draft

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Marcelo Mayer scouting report

Mayer is an all-around, five-tool player who provides patience, baserunning, defense and some power. The lefty hitter is still improving at the plate, but his strikeout rates have declined over the course of his minor league career, while his power has fluctuated.

Additionally, Mayer can play all over the infield and has played more second base recently, likely to prepare for this promotion. While he will probably slot in as Boston's long-term shortstop, Mayer will play more second and third base in the short term to fit into the lineup.

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Marcelo Mayer age

Mayer is 22 years old and won't turn 23 until December of this year, and will instantly become the youngest player on the Red Sox roster.

Marcelo Mayer injury history

Mayer's biggest issue in the minor leagues has been injuries, as he has only played 80 games in a season once so far. In 2023, Mayer had season-ending shoulder surgery, then in 2024, dealt with a variety of injuries that included a season-ending lumbar strain.

So far in 2025, Mayer has remained healthy and played 43 games in AAA through May 23rd.

MORE: Red Sox star Alex Bregman to miss time with right quad injury

Marcelo Mayer call up video

The Red Sox released the video of AAA manager Chad Tracy telling the shortstop that he will be getting called up ahead of Game 2 of Boston's doubleheader vs. Baltimore on Saturday.

Marcelo gets the call: pic.twitter.com/jVZDqRxKjP

— Red Sox (@RedSox) May 24, 2025

Marcelo Mayer stats