Mayer has shifted his rehab program to the Red Sox's facility in Florida and is not expected to return from Triple-A Worcester's 7-day injured list before the end of the season while he recovers from a lumbar strain, Alex Speier of The Boston Globe reports.
Promoted to Triple-A on Aug. 12 along with fellow top prospects Kyle Teel and Roman Anthony, Mayer has yet to debut for Worcester and will now have to wait until 2025 to do so. Mayer had produced an .850 OPS to go with 13 stolen bases in 335 plate appearances at Double-A Portland but hadn't played since July 30 due to what the Red Sox initially viewed as a short-term hip issue. With Mayer's effort to return to game action having plateaued in recent weeks, however, the 21-year-old was sent in for further medical evaluation, at which point he was diagnosed with the lumbar strain. On a positive note, Mayer is expected to make a full recovery from the injury and have a normal offseason, putting him on track to enter spring training without any restrictions.