Mariners' Phelps to undergo Tommy John surgery after tearing UCL

The Seattle Mariners bullpen suffered a significant blow Wednesday as reliever David Phelps will miss the entire 2018 season after tearing the ulnar collateral ligament in his right elbow.

Phelps suffered the injury during Saturday's outing and will now undergo Tommy John surgery.

"There's no way to sugarcoat it," general manager Jerry Dipoto said, according to Greg Johns of MLB.com. "He's a big piece of what we're doing here, and it's a big loss for us. He will feel it, his teammates will feel it, and we'll feel it. The good thing is we do feel we have some depth to work back from, but it won't be an easy spot to fill. There's a reason we went and got him, a reason we were excited for his return. He'll be missed."

The 31-year-old was acquired from the Miami Marlins last July and was expected to pitch in a late-inning role for the Mariners. In 54 appearances last season, Phelps posted a 3.40 ERA, 1.38 WHIP, and 62 strikeouts across 55 2/3 innings.