Red Sox place Marcelo Mayer on 10-day IL with bone stress reaction in left ulna, recall Tsung-Che Cheng

The Red Sox announced on Friday that shortstop Marcelo Mayer has been placed on the 10-day injured list with a bone stress reaction in the left ulna. The move impacts Boston’s infield picture, coming at a point in the season when everyday reps and defensive continuity matter for both run prevention and lineup stability.

Mayer’s IL placement describes a specific, localized stress injury to the left forearm bone rather than an open-ended, unspecified ailment. According to reporting from Chris Cotillo of MassLive, Mayer has been dealing with the issue for about two months. That timeline suggests the injury was not a one-week setback, but instead a lingering problem that ultimately required a formal shutoff to manage risk.

As the corresponding move, Boston recalled infielder Tsung-Che Cheng. The recall is tied to the roster requirement created by Mayer’s IL stint, and it indicates that the Red Sox are looking to maintain an infield option who can cover multiple roles depending on how the club uses the position group day to day.

Bone stress reactions can be particularly difficult to navigate because they often require rest and gradual reloading, even when a player is otherwise able to swing or move on a limited basis. For teams, that means the return plan is as important as the diagnosis. The Red Sox now need to bridge the playing-time gap with a shortstop replacement and an infield rotation that minimizes further strain on other players.

Mayer’s injury also carries lineup and development implications. As a shortstop, he typically sits at the center of how an infield handles range, throws, and quick transfers. When a player with those responsibilities goes on the IL, managers must adjust not just personnel but also the defensive assignments that shape innings-by-innings decision-making.

Cheng’s recall will be watched for how Boston distributes reps across the infield. The immediate question is whether he becomes a direct shortstop answer, a utility bridge, or a more situational option while Boston decides how to best protect matchups and defensive quality. Even if Mayer is away for only the minimum window, how Boston handles the gap can matter for momentum and for who earns additional responsibilities on the margins.

The next milestone is straightforward: once the IL window opens and Boston’s medical staff and coaching staff evaluate his progress, the club will need to decide whether Mayer can begin a controlled return to action. Until then, the Red Sox’s focus will be on keeping the infield functional with routine defensive execution and enough depth to absorb the everyday grind.