Anaheim Angels reliever Keynan Middleton to have Tommy John surgery

Los Angeles Angels right-handed reliever Keynan Middleton said Thursday he will undergo season-ending Tommy John surgery after a second opinion recommended the procedure.

The operation will repair damage to the ulnar collateral ligament in his right elbow.

The team announced Thursday evening that Middleton will meet with team doctors to discuss details and a timeline for his treatment. Tommy John surgery typically sidelines pitchers for 12 to 18 months.

Middleton leads the Angels with six saves in seven opportunities and a 2.04 ERA. Manager Mike Scioscia had not officially named him the team's closer, but he had increasingly used Middleton that way.

The 24-year-old spent 12 days on the disabled list with a sore right elbow before being activated May 10. He made three appearances in four days before returning to the DL, most recently pitching two-thirds of an inning on Sunday and then leaving the game with elbow discomfort. The final two fastballs he threw were at about 88 and 92 mph, well off his average of about 97 mph a season ago.

The team announced on Monday that Middleton had damage in his UCL.

Scioscia had been holding out hope that Middleton would not need UCL reconstruction, telling reporters Monday, "Let's not get ahead of ourselves."

The Angels have had a half-dozen pitchers deal with UCL injuries since 2014. That August, Tyler Skaggs underwent Tommy John surgery.

In April 2016, both Garrett Richards and Andrew Heaney sustained UCL injuries and underwent stem-cell therapy, with mixed results.

The treatment healed Richards' ligament, but Heaney ended up having Tommy John surgery. Nick Tropeano, who was diagnosed with a damaged UCL in July 2016, ended up having Tommy John surgery in August.

Richards sustained a separate injury last year.

Also, JC Ramirez, who was injured last August, tried stem-cell treatment and appeared to have avoided surgery, but last month he reinjured the ligament and had the surgery.

The Angels aren't lacking for pitchers with closer experience, such as Jim Johnson, Cam Bedrosian and Blake Parker. Rookie Justin Anderson is 1-for-2 in save chances, recording the team's most recent save on Monday in a 2-1 win over the Houston Astros.

"I think we have a lot of guys," Scioscia told the Orange County Register earlier this week. "I don't think we ever had one guy that was the ninth-inning guy. We've got some guys in the back end who are going to have to get outs for us. How they line up in a certain game will be dictated by how the game unfolds and the matchups. We're confident we have the arms down there that will get the outs we need."