Rays top pitching prospect Brent Honeywell has been diagnosed with a torn ulnar collateral ligament in his right elbow, tweets Marc Topkin of the Tampa Bay Times. Tommy John surgery has been recommended for the promising 22-year-old.

The diagnosis represents a worst-case scenario for the Rays in the wake of yesterday’s ominous arm injury for Honeywell. The early diagnosis was a forearm strain, though that’s often a precursor to a UCL tear upon further testing. Topkin noted yesterday that the injury was of “major concern” to the Rays. Honeywell reportedly threw roughly 10 pitches in a batting practice session before loudly shouting after his final pitch and eventually walking off the mound with a trainer.

The likely loss of Honeywell for the season is a brutal hit to the Rays’ depth. Even though Tampa Bay is hardly lacking for rotation alternatives, Honeywell ranks as not just one of the best pitching prospects in baseball but one of the top overall prospects in the game. Each of Baseball America, MLB.com, ESPN, Fangraphs and Baseball Prospectus ranked Honeywell within the top 15 overall prospects on their respective top 100 lists heading into the 2018 season.