The Phillies will be without one of their top offseason acquisitions for the rest of 2026.

Right-handed relief pitcher Brad Keller, who inked a two-year, $22 million deal with Philadelphia in free agency during the offseason, was placed on the 15-day injured list with a torn UCL in his right elbow, the team announced Thursday.

Keller, 30, already missed time earlier this season when the Phillies placed him on the IL in mid-June with right forearm tendinitis.

Brad Keller is out for the season for the Phillies. Getty Images

“He’d been having just little stuff going on, and it kind of continued,” interim manager Don Mattingly told reporters at the time. “It was something that we felt like we’re better off knocking it out right now and not letting it get too far.”

He returned before the All-Star break and made one appearance on July 8, tossing a scoreless inning in a 11-5 loss versus the Reds.

In 32 appearances this season, Keller posted a 4.02 ERA along with three saves.

Keller was a hot commodity this past winter, coming off a career year with the Cubs in which he notched a 2.07 ERA in 68 appearances.

The Yankees were among several teams that were interested in the longtime Royals hurler before he agreed to terms with Philadelphia.

Given the average recovery time for UCL surgery and the possibility of a lockout in 2027, it’s possible Keller will not pitch again until 2028.

The Phillies will kick off the second half on Thursday in Philadelphia against the struggling National League East rival Mets.

New York got a key player back from the IL on Thursday, with second baseman Marcus Semien reinstated and journeyman infielder Zack Short designated for assignment.