Jack Kochanowicz diagnosed with torn UCL, will need Tommy John surgery

ANAHEIM, Calif. – The Los Angeles Angels have received some disappointing news about one of the main pieces of their starting rotation. 

Jack Kochanowicz revealed on Tuesday that he received a MRI and was diagnosed with a torn ulnar collateral ligament and will "definitely" need Tommy John surgery, ending his season and facing him with what can be up to an 18-month recovery timetable.

"Honestly, I didn't think this was in the cards. I really thought it was just maybe a little angry," Kochanowicz said of his surprise at the diagnosis. "The fastballs, everything I'm fine. It was really just a change up, so I thought I was gonna hear back that it was all right." 

Suffering decline

Kochanowicz had been a pleasant surprise for the Angels at the beginning of the season with a 3.05 ERA through his first seven starts of the season, pitching through at least six innings in four of those starts. 

But, his performance gradually began to decline through the end of April onward with a 7.85 ERA in the month of May, eventually leading to his worst start of the season on June 6 against the Los Angeles Dodgers, where he allowed six hits and seven earned runs while recording just one out. 

Steven Park – The Sporting Tribune

Jack Kochanowicz #41 of the Los Angeles Angels pitches during an MLB game against the Toronto Blue Jays at Angel Stadium on April 21, 2026 in Anaheim, California.

Kochanowicz was placed on the 15-day injured list with "right elbow inflammation" the day after that start, culminating in his MRI and diagnosis now. 

Finding A Replacement

With the news being so fresh, the Angels now have to go searching for a new starter to fill Kochanowicz's spot. 

Sam Aldegheri was called up from Triple-A Salt Lake when Kochanowicz was first put on the IL and pitched one inning of relief against the Houston Astros on June 8, allowing one unearned run, but manager Kurt Suzuki said that he hasn't made any decisions on a set replacement starter quite yet.

"He [Aldegheri] pitched the ball really well last night too. So, he's an option," Suzuki said. "Guys are throwing in Triple-A that have done really well too. Just kind of seeing what gives us the best option."

Sujey Luna / The Sporting Tribune

Los Angeles Angels pitcher Sam Aldegheri (66) throws a pitch during MLB game against the Houston Astros on Friday, September 13, 2024 in Anaheim, California.

Among those options in Triple-A are pitchers like Caden Dana, George Klassen and Brett Kerry, who've all had varying levels of success with the Salt Lake Bees. 

Both Suzuki and Aldegheri were surprised at the extent of the injury considering that Kochanowicz's fastball velocity seemed unaffected in his most recent start, but Kochanowicz also revealed that he'd been feeling some arm discomfort for some time, but described it as "general soreness" rather than anything concerning that he felt could have predicted his injury now. 

Robert Sloter – The Sporting Tribune

Jack Kochanowicz #41 of the Los Angeles Angels reacts during a game against the Texas Rangers at Angel Stadium on July 10, 2025, in Anaheim, California.

The revelation of the injury also provides Kochanowicz some clarity to explain his recent struggles, though he naturally wishes that he didn't have to go through a season-ending injury to make that discovery.

"It's obviously tough and not what you want to hear more than anything," Kochanowicz said. "I'll just miss being here with all the guys… but it does give me a little bit of clarity, just because I've been grinding."