The Mets’ starting right-hander Frankie Montas has suffered a UCL injury in his right elbow, ending his season.

The New York Mets have added starting right-hander Frankie Montas to the 15-day injured list because of a right elbow UCL injury. In response, the club called up right-hander Huascar Brazobán from Triple-A Syracuse.

Montas underwent an MRI yesterday after experiencing soreness in the lower biceps area, which revealed the injury. Manager Carlos Mendoza confirmed that Montas’s season is over.

“During the game against the Washington Nationals, we had him warm up, but he obviously didn’t pitch,” Mendoza said. “When he came in yesterday, he mentioned some soreness in the lower biceps. He went out to throw, and we decided to send him for an MRI, which showed the UCL injury.”

Mendoza did not specify whether the injury was a tear or a strain and noted that he and Montas will consult with doctors before deciding on the next steps.

“He has a fairly serious injury,” Mendoza said. “We’ve had multiple doctors review it to understand what we’re dealing with. The initial MRI results indicate a significant injury, and Tommy John surgery is a possibility.”

For Montas, this continues a turbulent season. In nine games (seven starts), he posted an ERA of 6.28. Less than two weeks ago, the Mets moved him to the bullpen, with veteran Montas giving up his rotation spot to rookie Nolan McLean.

The Mets signed Montas to a two-year, $34 million contract during the offseason, hoping to stabilize their rotation. However, the 32-year-old suffered a high-grade lat strain on his right side during spring training, delaying his season debut by over three months.

“It’s been tough for him,” Mendoza said. “He was very upset when he got the news yesterday, understandably so. After being injured in spring training and spending a lot of time rehabbing, it’s been a difficult year. He came back but didn’t achieve the results he or we wanted. It’s really unfortunate that he struggled to recover after his last two appearances.”

Even when healthy, Montas did not provide the rotation boost the Mets had hoped for, contributing to the team’s surprising struggles in the starting pitching staff. Since June 13, the Mets’ starting pitchers have posted a combined ERA of 5.06, the third worst in the entire league.

On August 12, the Mets announced they were removing Montas from the rotation. Shortly before that, he gave up three runs (one earned) in three relief innings against the Brewers. However, his bullpen stint was brief: he only appeared once more on August 15 against the Mariners. Mendoza hinted that the injury might have affected Montas’s recent performances.

“The injury may be related to his recent outings,” Mendoza said. “His velocity remained, but the injury might have impacted his off-speed pitches. At the time, he didn’t feel anything unusual. It was only in the last few appearances—his last start and then moving to the bullpen—that he felt more soreness. The day after he didn’t pitch, he came in feeling ‘something was off.’ We didn’t think much of it then because it was around the biceps area.”

Brazobán was an important part of the Mets’ bullpen early in the season but later struggled again with control issues. This year, he has appeared in 44 games for the Mets, pitching 51.2 innings with a 3.83 ERA, but after being sent down on July 29, he posted a 6.75 ERA in seven games for Triple-A Syracuse.

“Part of the reason we sent him to Triple-A was to get him more innings,” Mendoza said. “We’ve increased his workload to nearly 40 pitches. If we need him for a longer relief role, we feel confident in him.”