Justin Slaten's Injury Costs Red Sox Dearly With Playoffs Looming

The Boston Red Sox likely won't have one of their best relievers back on the mound this season.

Jul 17, 2026; Boston, Massachusetts, USA; Boston Red Sox pitcher Justin Slaten (63) pitches during the eighth inning against the Tampa Bay Rays at Fenway Park. Mandatory Credit: Bob DeChiara-Imagn Images | IMAGN IMAGES via Reuters Connect

Over the last few weeks, or so, it has seemed like pretty much every injury update for the Boston Red Sox has been positive.

Garrett Crochet has been throwing, Tanner Houck has been on a rehab assignment and even Curtis Mead has been playing catch, among others. While this is the case, the Red Sox gave a negative update on Wednesday. Red Sox interim manager Chad Tracy shared that reliever Justin Slaten is dealing with "degenerative changes in the flexor mass" and is likely done for the 2026 season.

"Slaten, we got ... he went and saw [Dr. Keith Meister] with our medical staff today and there's some degenerative changes in the flexor mass," Tracy said. "So he's going to be down. He's going to get a PRP injection and it's likely going to end his season. So, that's substantially different news, as far as these guys."

Chad Tracy provides some #RedSox injury updates ⬇️

- Crochet threw today, everything went well
- Guerrero eligible tomorrow
- Rafaela started to increase running volume today, nothing new to report
- Houck is throwing tonight
- Slaten has "some degenerative changes in the flexor… pic.twitter.com/M04YHBmZCP

— NESN (@NESN) September 15, 2026

Bad News For Boston

Jun 27, 2026; Boston, Massachusetts, USA; Boston Red Sox pitcher Justin Slaten (63) pitches during the seventh inning against the New York Yankees at Fenway Park. Mandatory Credit: Bob DeChiara-Imagn Images | IMAGN IMAGES via Reuters Connect

This is a brutal blow for Slaten, and the Red Sox's bullpen in general. Slaten is one of the club's key high-leverage guys, but Boston hasn't had him on the mound since Aug. 12. He was initially placed on the Injured List due to right elbow inflammation. He actually started throwing, but he had to be shut down when the same "symptoms" that landed him on the Injured List popped up again.

Slaten had a 4.60 ERA in 36 appearances, but this doesn't tell the full story about why he's a big loss for Boston. In his final 17 appearances of the season, he had a 2.45 ERA and a 19-to-3 strikeout-to-walk ratio in 14 2/3 innings pitched. The first half of the season wasn't great for him, but he had turned things around and looked like the guy Boston hoped it would have out of the bullpen.

The Red Sox have just 11 games left in the 2026 regular season. Losing Slaten hurts Boston's playoff chances. On the bright side, the Red Sox's bullpen could still get better with Houck on a minor league rehab assignment and Garrett Crochet throwing as well. With Slaten likely out for the season, that's one less change Boston will have to make when building the playoff roster. Tyron Guerrero, Crochet, and Houck are all inching their way back. Boston will have to clear three spots to get these guys on the roster. That could be bad news for guys like Greg Weissert, Wyatt Olds, and Raymond Burgos, among others.

With Slaten likely not coming back, it's one less decision for Boston to make. Of course, it would be better if he were returning, but that isn't the case right now. Unfortunately, Red Sox fans have seemingly seen the last of Slaten for the 2026 season.