Red Sox move INF Marcelo Mayer to Giants for LHP Erik Miller

The Boston Red Sox boosted their bullpen with the acquisition of LHP Erik Miller & from the San Francisco Giants in return for INF Marcelo Mayer.

BY FIELD LEVEL MEDIA

Aug 4, 2026, 6:14 AM Updated: 6:15 am

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The Boston Red Sox boosted their bullpen on Monday with the acquisition of left-handed reliever Erik Miller and minor-league outfield prospect Carlos Gutierrez from the San Francisco Giants.

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.

Gutierrez, 21, ranked No. 14 among Red Sox prospects by MLB Pipeline after the trade, hit .271 with nine homers, 26 stolen bases and 45 RBIs in 83 games for High-A Eugene this season.

Marcelo Mayer is said to be enthused by the trade and a change of scenery out west. He’s excited about the new opportunity instead of being bitter about a lack of a long leash in Boston.

— Chris Cotillo (@ChrisCotillo) August 4, 2026

More on Marcelo Mayer

Marcelo 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, Marcelo 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.

Marcelo 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.

–Field Level Media