(Photo credit: Charles LeClaire-Imagn Images)

The Pittsburgh Pirates' National League wild-card aspirations took a hit on Monday with the news that right-hander Mitch Keller will miss the rest of the season due to a teres major muscle injury in his throwing shoulder.

Addressing the media on Monday, Pirates general manager Ben Cherington said he believes Keller sustained the injury during his road start Sunday against the Reds. Keller gave up seven runs, two homers and four walks in two-plus innings in a 10-2 loss.

'He wasn't reporting anything,' Cherington said. 'He did report it after coming out of the game (Sunday). So, it was certainly the first that I'd heard about it.

'Got more information (Monday) once we had the MRI. Now, just got to work with Mitch to get past this and get healthy and get into a really good offseason, which we're confident he'll do.'

The Sunday start derailed Keller's return to form, as the 30-year-old veteran had posted two solid outings, allowing two runs over 10 1/3 innings. Keller registered a 2.85 ERA over his first seven starts this year, but the ERA ballooned to 6.63 over his last 15 starts. Overall in 2026, he went 6-8 with a 5.29 ERA.

'Extremely tough to get the news on Mitch,' manager Don Kelly said following Pittsburgh's 4-3 win at Milwaukee on Monday. 'Frustrating for him, first, and then from a team aspect, it's tough. We've been fortunate, haven't been really hit on the offensive side injury-wise, pitching side a little bit, but to have a starter like Mitch go down, tough.'

Keller will not throw for six to eight weeks due to the injury.

Cherington deferred to Kelly when asked if Keller's injury meant Carmen Mlodzinski would return to the rotation. Pittsburgh's GM did mention that Keller's ailment played a role in the team acquiring right-hander Lake Bachar from the Marlins before the trade deadline on Monday.

In eight major league seasons, all with Pittsburgh after the team selected him in the second round of the 2014 draft, Keller is 48-73 with a 4.60 ERA in 187 games (185 starts). Over 993 2/3 innings, he has 926 strikeouts and 341 walks with a 1.381 WHIP.

--Field Level Media