Red Sox Promote Marcelo Mayer; Alex Bregman To IL With “Significant” Quad Strain

4:27pm: The Red Sox have officially announced the selection of Mayer’s contract. Bregman was placed on the 10-day injured list with a right quad strain to create room for Mayer on the active roster, while Casas was placed on the 60-day injured list to create a 40-man roster spot. Cora told reporters (including Jen McCaffrey of The Athletic) this afternoon that Bregman’s injury is “significant” and compared it to a quad strain Bregman suffered in 2021 that ultimately caused him to miss around two months.

1:39pm: The Red Sox are promoting top infield prospect Marcelo Mayer, reports ESPN’s Jeff Passan. Katie Morrison-O’Day of MassLive observed that Mayer was being congratulated by his teammates in the clubhouse at Triple-A Worcester. Her MassLive colleague Christopher Smith first reported that the former first-round pick is headed to Fenway Park.

The promotion comes as Alex Bregman navigates a right quad injury that seems likely to send him to the 10-day injured list. Bregman came out of yesterday’s blowout win over the Orioles in the fifth inning. He came up a bit gimpy after making an aggressive turn around the first base bag on a single off the Green Monster. He immediately exited in favor of Abraham Toro. The team is still awaiting MRI results from this morning. Manager Alex Cora told reporters (including WEEI’s Rob Bradford) that the star third baseman woke up with more soreness than he’d expected today.

Boston did not place Bregman on the IL before the first game of today’s doubleheader. There’s a good chance that’ll come between games tonight. They’ll also need to clear a spot on the 40-man roster for Mayer, but that can easily be achieved by transferring Triston Casas to the 60-day injured list.

Cora has already shot down the idea that Rafael Devers could see any third base time in Bregman’s absence. He’ll remain a full-time designated hitter. That means the 22-year-old Mayer should be in the lineup on a near everyday basis at third base. He obviously can’t be expected to replace the production they’re losing with Bregman’s absence. The two-time All-Star takes a .299/.385/.553 batting line to his likely stint on the injured list.

Mayer has very little experience at the hot corner. He started one game there in Double-A in each of the 2023 and ’24 seasons. He’s added four appearances in Triple-A this year. Mayer has taken the vast majority of his professional reps as a shortstop. He’d moved more frequently to second base over the past few days. That wasn’t because of any question about whether he can hold up at shortstop. It was instead in preparation for what seemed to be his best path to an MLB debut — playing second base with Kristian Campbell preparing to slide to first base after the Casas injury.

While there may be some growing pains given Mayer’s lack of experience at the hot corner, it’s common for shortstops to move to other infield positions. He has the plus arm for the position and is generally regarded as a sure-handed infielder. At 6’3″, Mayer is on the bigger side for a shortstop. His range, while adequate, has never been the strongest point of his defensive profile. That’s less of a concern at third base.

Mayer certainly brings a higher offensive ceiling than the utility options (Toro and David Hamilton) who may otherwise have replaced Bregman. The fourth overall pick in 2021, Mayer has been a feature on top prospect lists throughout his professional career. The left-handed hitter has moved a little more slowly than anticipated, largely because of injuries to his left shoulder and right wrist that affected him in 2022-23. Scouts have remained enamored with his power, polished strike zone discipline and overall natural athleticism.

That has been on display over the past two minor league seasons. Mayer hit .307/.370/.480 in Double-A a year ago. He’s out to a solid .271/.347/.471 slash with nine homers in 43 games during his first Triple-A action. He’s drawing walks at a strong 10.4% clip compared to a 19.7% strikeout rate that matches last year’s mark for the lowest of his career.

While the Bregman injury is the immediate impetus for Mayer’s promotion, there should be opportunity to stick past Bregman’s return if he performs well. The Sox may feel comfortable using Campbell at first base by that point, potentially opening second base. Mayer could also eventually supplant Trevor Story as the starting shortstop. Story began the season with a power barrage but has done almost nothing offensively for the better part of six weeks. He’s hitting .159 with one home run and 38 strikeouts in 122 plate appearances since his two-homer game on April 18.

Mayer will not reach a full year of service time unless he triggers the Prospect Promotion Inventive by finishing in the top two in Rookie of the Year voting. The Sox would not receive an extra draft choice under the PPI because they did not carry Mayer on the big league roster for at least 172 days. He would be on track to qualify for early arbitration as a Super Two player during the 2027-28 offseason if he’s in big leagues for good, though future optional assignments could certainly change that timeline.

Photo courtesy of Imagn Images.