With Alex Bregman signing a five-year, $175 million contract with the Chicago Cubs, the Boston Red Sox are now in an unenviable situation. The third base position is completely unsettled, just one year after it appeared the team had two franchise-caliber options (Bregman and Rafael Devers) at the position. Now, they’ll likely have to entrust the future to an unproven youngster. That latter qualification is especially applicable when it comes to their former top prospect, Marcelo Mayer.
Mayer, who was originally drafted as a shortstop and viewed as the heir apparent to the position, has been blocked there due to a combination of Trevor Story along with his own health issues. Making his major-league debut in 2025, Mayer played the majority of his games at third base when Bregman was out with a quad injury.
In total, Mayer appeared in 44 games with the Boston Red Sox in his rookie season, 39 of them involving an appearance at third base. And despite playing the position just six times prior to the promotion, Mayer played well enough defensively to hold down the position until Bregman’s eventual return from the injured list — he made only made one error in 68 opportunities. Add to it that his fielding run value was 2.0 while his total defensive run value was 3.0, and you have some concrete proof that Mayer took to the position rather well.
There is no denying that losing Bregman will be a big blow to the team, from both a leadership standpoint along with his bat. However, Mayer should be able to handle picking up the slack on the defensive end. He had always been viewed as an above-average defender and that much was shown in 2025. Where the team will be asking for Mayer to truly step up will be on the offensive end.
The infielder will be entering his age-23 season and what will likely be his first full season in the majors. What will be a detriment for Mayer will be his injury history that limited his development in the minors. Since being drafted in 2021, Mayer appeared in 315 games across five minor league seasons, including a career-high 91 games in 2022. Besides a rough stretch in 2023 with Portland where he slashed .189/.254/.355, which was due in part to trying to play through an injury, Mayer has looked good at the plate. However, his missed development time was on display while facing major-league pitching while with Boston.
In his time with the Red Sox last season, Mayer slashed .228/.272/.402 with eight doubles, a triple, four home runs and 10 RBIs. He also struck out 41 times while walking just eight times; overall Mayer walked at a 5.9% rate while striking out in 30.1% of his plate appearances. Taking his age into consideration, Mayer has plenty of room to improve upon those numbers. And for the Red Sox to play well, he’ll have to. Of course, it could be argued that once Mayer was finally getting used to the quality of pitching in the majors, his injury occurred. In the month of July, he was beginning to heat up, as he slashed .244/.277/.333 with four doubles and three RBIs.
The Red Sox will need Mayer to step up into a prominent role this year, perhaps more than anyone thought at the onset of the offseason. But after losing Bregman, the team may look to hand the long-term keys to the hot corner to their budding young star.
Mayer, who has performed well at every stop in his minor-league career and has rebounded from struggles, will need to build off of his shortened rookie season and make a leap at the plate. Defensively, he has shown he is more than capable, but now it’s time for his offensive potential to be consistent. It’s a lot to ask of a player with such limited time in the pros, but losing two franchise superstars at one position in such a short time is almost impossible to recover from. Mayer is the Red Sox’s best chance at somehow escaping that debacle unscathed.