Baltimore Orioles veteran right-handed pitcher Zach Eflin will undergo a lumbar microdiscectomy and miss the remainder of the season, interim manager Tony Mansolino said Tuesday.

Mansolino also told reporters that right-handed closer Felix Bautista will not return this season due to a shoulder injury the manager deemed "significant."

Eflin, 31, was placed on the injured list three times this season, the latter two stints due to low back discomfort. He appeared in just two games in July and hasn't pitched since July 28.

A lumbar microdiscectomy is a procedure that addresses herniated disks in the lower back.

The Orioles acquired Eflin from the Tampa Bay Rays before the 2024 trade deadline and his first full season in Baltimore didn't go to plan. He went 6-5 with a 5.93 ERA in 14 starts, yielding 18 home runs and striking out 50 across 71 1/3 innings. His WHIP of 1.416 was the highest of his career.

Bautista, 30, was placed on the IL July 24 (retroactive to July 21) with discomfort in his pitching shoulder. Mansolino told reporters the team did not yet have a recovery timeline for Bautista.

Bautista made the American League All-Star team in 2023 and finished 11th in Cy Young Award voting after posting a 1.48 ERA and 33 saves in 56 games. He missed the entire 2024 season following Tommy John surgery.

In 35 appearances this season, Bautista was 1-1 and had 19 saves with a 2.60 ERA. He also walked 23 batters in 34 1/3 innings -- nearly doubling his previous career walk rate.