Top Red Sox prospect Marcelo Mayer shut down for rest of season

Top Red Sox prospect Marcelo Mayer has been shut down for the remainder of the minor-league season, director of player development Brian Abraham told MLB.com’s Ian Browne on Wednesday.

Mayer, who has been on Double-A Portland’s injured list with left shoulder inflammation, will not suit up for the Sea Dogs again this year. The 20-year-old shortstop will instead head to Fort Myers, Fla. to continue his rehab and focus on having “a full, normal offseason,” per Abraham.

According to The Boston Globe’s Alex Speier, Mayer was expected to return to action at some point last month. But upon resuming baseball activities, the left-handed hitter reaggravated the injury — which affects his ability to swing a bat — and has been idle ever since.

Abraham told Speier that Mayer is expected to ramp things back up in the coming days, adding that Boston’s No. 1 prospect will likely take part in the club’s fall instructional program at the Fenway South complex beginning next week.

“We just didn’t want him to play when he’s less than 100 percent,” Abraham said of Mayer. “Ultimately, we felt like having him be 100 percent during all activities was really important for him and for us.”

Mayer, the fourth overall pick in the 2021 draft out of Eastlake High School (Chula Vista, Calif.), earned a promotion to Portland in late May after batting .290/.366/.524 with 11 doubles, one triple, seven home runs, 34 RBIs, 23 runs scored, five stolen bases, 17 walks, and 37 strikeouts in 35 games (164 plate appearances) for High-A Greenville to kick off his second full professional season.

Upon being inserted into the Sea Dogs’ lineup, though, Mayer struggled to a .189/.254/.355 slash line with eight doubles, one triple, six homers, 20 runs driven in, four stolen bases, 15 walks, and 49 strikeouts in 43 games (190 plate appearances). He was in the midst of a 1-for-21 slump at the plate prior to hitting the injured list.

Despite the poor offensive numbers in Portland, Mayer showed signs of promise in other areas and represented the Red Sox at the All-Star Futures Game in July. On the other side of the ball, for instance, he committed just three errors across 323 innings at shortstop with the Sea Dogs. To that end, the 6-foot-2, 188-pound infielder was recently identified by Baseball America as the best defensive shortstop in both the South Atlantic (High-A) and Eastern League (Double-A) this year.

“It was a really positive [year], getting all the way up to Double-A at his age,” said Abraham. “He was probably a little unlucky. He put the ball in play, hit the ball hard, and played a really good defensive shortstop.

“Overall,” Abraham continued, “the chance to get to Double-A where he had a chance to be an impactful player on a team that was having a lot of success, it was a really good opportunity for him to play with some upper-level talent, see upper-levels pitching, and really play as if he belongs.”

It remains to be seen if Mayer, who turns 21 in December, will play in the Arizona Fall League, which gets underway next month. That being said, Speier notes that an AFL assignment “would be a consideration” if the California native gets back to 100 percent health-wise.

As things stand now, Mayer is currently regarded by Baseball America as the No. 15 prospect in the sport. MLB Pipeline, on the other hand, has him ranked 11th. Barring a surprise, Mayer is expected to return to Portland for the start of the 2024 season next spring.