The Boston Red Sox boosted their bullpen on Monday with the acquisition of left-handed reliever Erik Miller from the San Francisco Giants, per multiple reports.
The Giants received infielder Marcelo Mayer, who has long been considered one of the Red Sox’s ballyhooed prospects, to complete the deal.
Miller, 28, posted a 2-0 record with a 2.76 ERA and four saves in 38 appearances for the Giants this year. He has averaged 12.4 strikeouts and 6.1 walks per nine innings during his 32 2/3 innings of work.
Mayer, 23, has yet to fulfill his promise at the major league level since becoming the No. 4 overall pick in the 2021 MLB Draft.
Prior to the 2024 season, Mayer was listed by MLB.com as the game’s No. 15 prospect–directly ahead of Chicago Cubs outfielder Pete Crow-Armstrong and Baltimore Orioles catcher Samuel Basallo and directly behind Detroit Tigers outfielder Max Clark and Washington Nationals outfielder Jason Wood.
While those four have made an impact with their teams, Mayer has recorded a .223/.278/.346 slash line in 114 games for the Red Sox since making his debut at the start of the 2025 season. He has posted seven home runs and three stolen bases in 364 plate appearances.
Mayer has not appeared in a game since June 25 due to a bone stress reaction in his left forearm. He remains on the 10-day injured list.
