Padres' Jose Castillo to undergo Tommy John surgery

Injuries hit the San Diego Padres' bullpen hard Thursday.

Left-hander Jose Castillo will undergo Tommy John surgery to repair a torn ulnar collateral ligament in his left elbow, the team announced, according to AJ Cassavell of Castillo miss the entire 2021 season as a result.

Castillo felt forearm tightness Tuesday during a simulated game, according to Cassavell. He left the field with trainers for further examination after throwing his sixth and final pitch of the session, and the tear was discovered.

The 25-year-old was an important part of San Diego's bullpen as a rookie, crafting a 3.29 ERA and 0.91 WHIP across 38 1/3 innings in 2018. But a variety of injuries - including a left flexor tendon strain, a lat strain, and a finger injury - have limited Castillo to just two-thirds of an inning since then. He last made a big-league appearance in August 2019.

Castillo wasn't the only reliever the Padres lost Thursday. Right-hander Javy Guerra will miss two-to-four weeks after sustaining a Grade 1 UCL sprain, according to Kevin Acee of the San Diego Union-Tribune. That timeline likely means the 25-year-old will start the season on the injured list.

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