Just last year, the entire baseball world viewed Boston Red Sox infield prospect Marcelo Mayer as untouchable.

Fast forward to the present day, and Boston has ultimately decided to give up on Mayer, as he was shipped to the San Francisco Giants ahead of the 2026 MLB trade deadline.

Erik Miller is the return piece for the Red Sox

In exchange for Mayer, the Giants sent left-handed reliever Erik Miller to Boston. Miller has been among the best left-handed relievers in baseball this season and will be an excellent addition to the Red Sox bullpen.

A Marcelo Mayer trade is a bit shocking

Mayer was a prized possession in Boston just last season, so for him to be moved just a season later feels shocking.

His struggles across two seasons certainly played a role in the decision, as Mayer had managed to slash just .223/.278/.346 in his first 332 at-bats.

Erik Miller and Aroldis Chapman are an outstanding left-handed duo

Miller has limited opponents to just a .181 average this season, good for the 98th percentile in the majors. His 31.7% strikeout percentage is also elite, ranking in the 95th percentile this season.

Pair that with closer Aroldis Chapman, who ranks in the 97th and 95th percentile in those respective categories, and the Red Sox all of a sudden have what could be argued as the best left-handed reliever bullpen duo in the league.

The hottest team in the league added another piece that may help contribute to one of the most improbable turnarounds in MLB history.