May 24 has been a momentous day in Marcelo Mayer's career. In 2025, Mayer made his MLB debut on May 24, and on that date in 2026, he made his first career start at shortstop. Being platooned and injuries have meant he hasn't reached 100 games played yet, but even with a lack of games, opponents have highlighted a major weakness in his game.
The Red Sox selected Mayer with the fourth overall pick in the 2021 MLB Draft out of Eastlake High School in Chula Vista, California. Mayer was MLB Pipeline's No. 1 player in the draft that year. While draft projections thought he could have "a Corey Seager-like offensive profile" in the minors, the bat wasn't his calling card. He was never a below-average bat, but his best single season was a .307 average with an .850 OPS in Double-A Portland in 2023, though he only played 77 games.
His defense has always been his standout ability, and it is what moved him quickly through the minors. Those with knowledge of the Sox minors didn't think Mayer was ready for the call-up when he got it due to his bat, but the Sox forced him in when Alex Bregman got injured.
In the calendar year since his call-up, it seems like pundits were right about his bat. Mayer has been a .222 hitter with a .579 OPS. Worse than that, Boston's shortstop of the future has struggled mightily against offspeed pitches. Baseball Savant defines an offspeed pitch as all changeups, splitters, or forkballs.
Opposing pitchers might have found Red Sox infielder Marcelo Mayer's Achilles Heel
Last year, Marcelo Mayer saw offspeed pitches 17.3% of the time. He hit .125 against them with a .292 SLG. 42.6% Whiff%.
— Tyler Milliken (@tylermilliken_) May 25, 2026
So far in 2026, he’s seeing them 27.9% of the time. He’s batting .057 against them with an .086 SLG. 41.1% Whiff%. pic.twitter.com/IdBvOhzXEW
As pointed out on X by Section 10's Tyler Milliken, Mayer had a hard time last year against offspeed, and this year, pitchers are really attacking and pinpointing that weakness. He is saw 5% more offspeed pitches in May than he did in April, which could be one of the reasons Mayer is the third-worst qualified hitter in MLB by wRC+ since the beginning of last month. Opponents are especially using offspeed late in counts this year, too. He is seeing offspeed pitches 35.5% of the time in two-strike counts and is hitting just .182 in those situations.
One of the biggest red flags for Mayer is his average launch angle against offspeed. In 2025, Mayer had a 14-degree launch angle, meaning he was hitting mostly line drives. In 2026, that number is down to -8 degrees, meaning he is getting on top of them and hitting them straight into the ground.
Mayer is still only 23. He has time to figure it out in the majors, and his elite defense will extend his leash. He needs to fix this problem, though. MLB pitchers are elite at attacking and exploiting a weakness. If he wants to live up to his draft hype and his top-10 prospect pedigree, this is something he needs to get on top of.
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