Diamondbacks righty Humberto Castellanos to undergo Tommy John surgery

Diamondbacks right-hander Humberto Castellanos will undergo Tommy John surgery, manager Torey Lovullo announced (via Steve Gilbert of MLB.com). The 24-year-old is already on the 60-day injured list, having missed the past couple months with an elbow strain.

Castellanos’ efforts to avoid going under the knife will prove unsuccessful, and he’ll likely miss all of next season recovering. It’s a hit to the club’s rotation depth, as the Mexican-born hurler has started 16 of his 25 outings for Arizona over the past two years. Castellanos, who also made eight relief appearances with the Astros during the shortened 2020 season, was a Jan. 2021 waiver claim.

The 5-foot-11 hurler has tossed 100 2/3 innings at the major league level, working to a 5.45 ERA. He doesn’t throw hard, with his fastball typically clocking in the 89-90 MPH range. That has translated to a lack of missed bats, with Castellanos generating swinging strikes at a meager 7.2% clip. He’s a plus strike-thrower, though, walking only 7.3% of batters faced in the big leagues.

Castellanos will be paid at the MLB minimum rate and collect big league service time for the remainder of the season. He’ll have to be reinstated from the injured list at the start of the offseason. He won’t be arbitration-eligible until the end of next year, so the D-backs could affordably keep him around if they’re willing to devote him a 40-man roster spot over the winter.