PEORIA, Ariz. (AP) — Mariners reliever David Phelps will miss this season after tearing the ulnar collateral ligament in his pitching arm.

Seattle general manager Jerry Dipoto announced the diagnosis Wednesday night.

Phelps was injured on the final pitch of his previous outing March 17 against the Angels. The right-hander will have Tommy John surgery to repair his elbow, though a surgery date has not been set. The typical recovery time for that operation is 12 to 15 months.

The 31-year-old Phelps was 2-1 with a 3.12 ERA in 10 relief appearances with Seattle after a trade from Miami last July. He did two stints on the disabled list with elbow issues last season. Phelps figured to be a key piece in Seattle’s bullpen this season.