Red Sox trade former top prospect Marcelo Mayer to Giants for left-handed reliever Erik Miller and outfield prospect Carlos Gutierrez

The Boston Red Sox traded infielder Marcelo Mayer to the San Francisco Giants for left-handed reliever Erik Miller and outfield prospect Carlos Gutierrez. Mayer, the fourth overall pick in 2021, struggled to establish himself at the major-league level, posting a .220/.282/.312 line in 228 plate appearances this season and spending time on the injured list with a forearm stress reaction. The Giants, who recently dealt Luis Arraez to Philadelphia, plan to evaluate Mayer at second base once he is healthy and retain his club control for at least five years.

Miller, a 28-year-old left-hander who has spent his entire big-league career with San Francisco, recorded a 2.76 ERA, four saves and ten holds in 38 appearances last season. He strikes out 32% of batters and induces ground balls at a 54% rate, though his walk rate remains high at 16%. The Sox expect Miller to compete for a late-inning role and added him to a bullpen that already includes Jovani Moran as a left-handed setup arm.

The third component of the deal, Carlos Gutierrez, is a 21-year-old left-fielder playing in High-A. He posted a .271/.385/.441 slash line with nine home runs and 26 stolen bases in 28 attempts. Rankings from FanGraphs and Baseball America placed him among the top prospects in the Giants’ system, and Boston appears confident in his hitting ability despite limited physical tools.

Boston’s front office, led by chief baseball officer Craig Breslow, indicated that Mayer was no longer viewed as a cornerstone of the franchise, with shortstop prospects such as Franklin Arias and established players like Trevor Story ahead in the depth chart. The trade gives the Red Sox additional bullpen depth while allowing the Giants to acquire a former top prospect who could contribute once he returns to health.