There was a point when Marcelo Mayer was viewed as the shortstop of the future for the Boston Red Sox.
Boston had one of its worst seasons in recent memory in 2020 and landed the No. 4 overall pick in the 2021 Major League Baseball Draft as a result.
That pick was used to select Mayer out of Eastlake High School (Chula Vista, CA) and the buzz intensified. The sweet-swinging lefty immediately was viewed as the heir apparent at shortstop, but injuries and inconsistent play in the big leagues changed things.
When healthy, Mayer has all of the upside in the world. He's just 23 years old and he tore his way up through the minors thanks to his smooth fielding and above-average bat. Multiple injuries slowed down his progression to the big leagues, though.
In 2025, he finally made the jump to the bigs, but his season was cut short due to injury. In 2026, he was healthy to kick off the campaign and he slashed .220/.282/.312 with a .594 OPS, three home runs and 22 RBIs before getting hurt again.
His trade value plummeted to the point that the Red Sox were willing to trade away a former top prospect for a reliever. Not the expectation, to say the least. But it's real. On Wednesday, the first photo of Mayer in a San Francisco Giants uniform popped up on social media.
Marcelo Mayer in a Giants uniform 👀
— Baseball America (@BaseballAmerica) August 12, 2026
(📸 Bill Mitchell) pic.twitter.com/cB1aKjWPxZ
Unfortunately, things just didn't work out.