Marcelo Mayer was once one of the top prospects in the Red Sox organization and was seen as a big piece of their future.
However, he was not producing offensively in the big leagues and spent a ton of time on the injured list. He had a .223 batting average with the Red Sox in 114 games. Although the young left saw fewer opportunities against southpaws, his numbers against lefties were much better than his numbers against righties.
This season was a similar story. He had a .471 average with two homers against lefties, but only had 18 plate appearances. In 210 plate appearances against right-handed pitching, he had just one home run. The San Francisco Giants sent him on a rehab assignment to Triple-A Sacramento, and he homered off a righty in his second at-bat.
It has to be at least a little bit frustrating for the Red Sox to see him do that, but they are likely not sweating it. They got Erik Miller in exchange for him, and he has not allowed a run in four outings in a Red Sox uniform. Additionally, Mayer was not going to have a real role when he was healthy.
Trevor Story was going to be the shortstop when he was healthy, and long-term, Franklin Arias seems to be the answer there. At second base, the Red Sox acquired Curtis Mead, and he is under contract for the next few seasons.
Trading Mayer was the right move, and one Triple-A home run will not change that fact. Mayer was a great hitter in Triple-A for the Red Sox organization as well. The real test will be whether he can figure out big-league pitching in a much more pitcher-friendly ballpark.