Mitch Keller's 2026 season ended with a Grade 3 teres major tear; no surgery required

What happened

Mitch Keller's 2026 season ended the day before the trade deadline, when the Pittsburgh Pirates placed him on the 60-day injured list with a teres major strain in his right shoulder. At the time, the club did not provide detailed specifics. Per MLB.com's Aiden Stepansky, Keller is believed to have suffered a Grade 3 strain — a severity that involved the teres major muscle detaching from the bone entirely. Remarkably, per the report, Keller did not require surgery. Doctors instead recommended a lengthy period of rest and rehabilitation, and he is expected to resume throwing late this month, with a normal offseason expected to follow.

The injury, per Stepansky's reporting, does not appear to have originated on a single pitch. Keller told Stepansky he could not pinpoint the exact moment it occurred — a detail that suggests he was pitching through discomfort for an extended stretch before the placement. That is the kind of revelation that reframes an entire season in retrospect.

Why it matters

The teres major is a rotator-adjacent muscle that plays a meaningful role in a pitcher's arm action, and a Grade 3 strain — full detachment — is about as serious as soft-tissue shoulder injuries get. The absence of a surgical recommendation is the most consequential detail in Steve Adams's piece at MLB Trade Rumors: it keeps Keller's offseason timeline intact and, assuming recovery continues without issue, leaves him positioned to slot back into Pittsburgh's rotation for 2027.

That rotation is worth protecting. The Pirates have assembled a genuinely young and intriguing group around Keller — Paul Skenes, Braxton Ashcraft, Jared Jones, and Bubba Chandler are all part of the picture — and at 30 years old, Keller is, per Adams, the clear elder statesman of that group. His experience and track record give the unit something the others are still accumulating.

There is also a financial dimension. The Pirates still have Keller under contract for two more years at a total of $38MM, per the report. For a small-budget club, that is a meaningful commitment, and the combination of a poor performance this season, a season-ending injury, and money remaining on the deal makes a robust trade market for Keller this winter difficult to envision, as Adams notes. The more straightforward path is a healthy return that restores his value — to the Pirates and, eventually, to whatever market exists for him.

The numbers

The season line tells the story of a pitcher working through something he could not name. Keller posted a 5.29 ERA across 22 starts — a significant departure from the pitcher who logged 707 2/3 innings with a 4.15 ERA and strong rate statistics from 2022 through 2025, averaging 177 innings and 31 starts per season over that span, per Adams.

The velocity data is particularly telling. Keller's average fastball sat at 93.3 mph this season, a career-low mark. In his final start before landing on the injured list, that number had dropped to 91.9 mph — also a season-low. Velocity decline of that kind, in hindsight, reads less like a mechanical issue and more like a body protecting itself.

The strikeout rate followed. Keller's 17.7% strikeout rate this season was a career-worst. His walk rate of 8.3%, while still described as solid in the reporting, was his highest since 2022 — a notable step back from the sub-7% marks he posted each year from 2023 through 2025. Taken together, the numbers sketch a pitcher whose stuff was quietly eroding well before the IL placement made it apparent.

Where the club stands

Pittsburgh finished at 82-80 (.506), third in the NL Central and eliminated from both the division and Wild Card races — the latter by 6.0 games relative to the cut line, per the season standings. The offseason now becomes the operative arena, and Keller's health trajectory is one of the more significant variables the front office will be managing. A rotation that includes Skenes, Ashcraft, Jones, and Chandler has obvious upside; adding a healthy, experienced Keller back into that mix would give the Pirates something they did not have for most of this season.

The $38MM remaining on Keller's deal is the other variable. Per Adams, if Keller can return to his prior form, that figure should not be prohibitive even for a small-budget club. The qualifier — "if" — is doing real work in that sentence, and it will continue to do so until Keller is back on a mound throwing at something resembling his previous velocity. The club enters the offseason on a one-game winning streak, which is, at minimum, a pleasant note to close on.

Is Esmerlyn Valdez ready for next year?

Per his own account, yes. Outfielder Esmerlyn Valdez wrapped up the season on the injured list with a hamstring strain, but he told MLB.com's Jason Mackey that he is healthy now and does not expect any lingering issues heading into next year. Valdez described running, hitting, and tracking balls in the outfield without difficulty, telling Mackey that everything has been going well. The hamstring concern, at least as Valdez describes it, appears to be behind him — a thread worth noting given that, per Stepansky's broader reporting at MLB.com, the Pirates are navigating multiple health situations heading into the offseason.

What we don't know yet

The Grade 3 characterization carries an important qualifier: Keller is "believed" to have suffered that severity of strain, per Stepansky's reporting. That is not a formal club announcement of a diagnosis, and the distinction matters when projecting timelines. The expectation that Keller will resume throwing late this month is also framed as a plan — not a completed milestone. Whether that timeline holds, and what the throwing program looks like once it begins, remains to be seen.

The trade question is similarly open. Adams notes that a strong market for Keller this winter is hard to imagine given the injury, the results, and the contract, but "hard to imagine" is not the same as "impossible." Offseason markets have a way of producing unexpected interest, particularly for pitchers with Keller's pre-season track record.

What to watch

The most immediate thing to monitor is whether Keller does in fact resume throwing this month as expected, and how that process unfolds. A pitcher coming off a muscle detachment — even one that reportedly did not require surgery — faces a meaningful test in the early throwing stages, and any setback there would reshape the offseason calculus considerably.

Beyond Keller, the Pirates' rotation construction for next season is worth tracking as a whole. Skenes, Ashcraft, Jones, and Chandler represent a young core with real depth, and how the front office chooses to build around them — whether through Keller's return, external additions, or some combination — will define a significant portion of Pittsburgh's competitive outlook heading into next season.

Valdez's offseason development is a quieter thread to follow. With a hamstring issue now reportedly behind him, he enters an important stretch. The Pirates will be watching, and so will the rest of the NL Central.