Justin Slaten’s 2026 season is over, and the Boston Red Sox delivered the news Tuesday, the same day that Slaten celebrated what should have been a happy item of personal news. Sept. 15 is Slaten’s 29th birthday.
Interim manager Chad Tracy told reporters Tuesday that an orthopedist visit turned up “degenerative changes” in Slaten’s flexor mass, a finding that required a platelet-rich plasma (PRP) injection and closed the door on any late-season return, Tracy said, according to a report by MassLive Red Sox beat writer Chris Cotillo.
The diagnosis capped weeks of failed attempts to get Slaten back on a mound, and it’s now the fourth time in three major league seasons he’s landed on Boston’s injured list. Tyler Milliken of the “Section 10” podcast confirmed the Slaten update on Tuesday afternoon.
Justin Slaten’s Elbow Injury History
Slaten last pitched Aug. 12 at Toronto, working a scoreless inning, according to ESPN’s game log for the right-hander. He went on the 15-day injured list four days later, retroactive to Aug. 13, with right elbow inflammation.
Slaten had dealt with elbow flare-ups more than once during 2026, bouncing back quickly the first couple of times before outings against the Athletics on Aug. 8 and Toronto on Aug. 12 left him worse for wear, according to the Boston Globe‘s initial injury report. A bullpen session that Saturday, meant to get him back on track, only highlighted the severity of his problem.
Boston had already pulled the plug on his throwing program by early September, a move that had the season’s outcome trending toward the worst-case scenario days before Tuesday’s exam confirmed it, according to CBS Sports’ reporting. As of Sept. 13, the club still listed him on the 15-day injured list with elbow inflammation, according to MLB.com. Slaten finishes the year with a 4.60 ERA over 31 1/3 innings across 36 appearances, striking out 39 and walking eight.
Justin Slaten’s Injury-Riddled Red Sox Career
This marks Slaten’s third straight season interrupted by injury. He missed roughly six weeks in 2024 with right elbow inflammation, lost most of three months in 2025 to a right shoulder issue, and went on the injured list in April 2026 with an oblique strain before the elbow problem resurfaced in August.
Slaten told the Globe back in May that injured list stints “never get any easier,” adding, “If anything, it gets worse.”
The Texas Rangers drafted Slaten in the third round in 2019, signing him for $575,000, according to Spotrac‘s contract and draft records. The Mets selected him in the 2023 Rule 5 draft and immediately flipped him to Boston, where he had to stay on the active roster all season.
His major league debut came against Seattle in March 2024, and it didn’t go smoothly — he surrendered the walk-off hit in extra innings. He got a measure of payback less than 24 hours later, finishing off a Red Sox win. That first full season remains his best with 44 appearances, a 2.93 ERA and 13 holds that earned him the club’s Fireman’s Award.
His career line now stands at 116 games, a 3.73 ERA and five saves across parts of three seasons.
The 6-foot-4 right-hander grew up in Longview, Texas, and pitched collegiately at the University of New Mexico before Texas took him in the draft, according to Fox Sports’ biography of the reliever. No birthday message appeared on the Red Sox’s official social accounts Tuesday, even as the club closed the book on Slaten’s year.
Justin Slaten Personal News Emerges Same Day Red Sox Rule Him Out for Season