LOS ANGELES -- Emmet Sheehan, an important starting pitching depth option for the Los Angeles Dodgers, underwent surgery to repair an ulnar collateral ligament Wednesday and won't pitch this season, the team announced.

Sheehan, 24, posted a 4.92 ERA in 60 innings in his first season in the majors last year, striking out 64 batters and walking 26. He entered spring training this year vying for one of the Dodgers' final rotation spots, but experienced forearm inflammation during his first bullpen session and began the season on the injured list. He then ramped back up to the point of facing hitters but was shut down again in early April.

Dodgers manager Dave Roberts, speaking before the start of a homestand Thursday, said Sheehan simply "wasn't responding the way we had hoped," making surgery -- either the popular Tommy John procedure or some hybrid version of it -- the logical outcome.

The Dodgers, riding a franchise-record 22-game streak of allowing four runs or fewer, are set in their major league rotation with Tyler Glasnow, Yoshinobu Yamamoto, Walker Buehler, James Paxton and Gavin Stone.

Bobby Miller, out since April 10 with shoulder inflammation, threw two innings of live batting practice in Arizona on Wednesday and could soon go out on a rehab assignment. Clayton Kershaw, recovering from offseason shoulder surgery, is expected to join the rotation at some point in the second half.