It's a disheartening setback for the highly touted southpaw, and for the many fans who were yearning to see him make his big league debut this season. Puk, who is slated to begin a lengthy rehab process in Arizona on Thursday, was expected to earn a promotion within the first few months of the season.
Puk opened Cactus League play with 10 consecutive scoreless innings, before unraveling in his final outing March 15 while showcasing diminished velocity. Less than two weeks later, the A's announced that Puk had torn his ulnar collateral ligament.
Dr. James Andrews was consulted after an initial diagnosis by Dr. Doug Freedberg, and it was recommended that Puk opt for Tommy John surgery.
"He was on what looked to be the fast track," A's manager Bob Melvin said at the time. "Now, obviously, a little bit of a setback, but he's still a young kid and he's still going to have a long, successful career, in my opinion."
The A's selected Puk with their first-round Draft pick (sixth overall) out of the University of Florida in 2016. He has 224 strikeouts in 157 2/3 professional innings, finishing the 2017 season at Double-A Midland.
Jane Lee has covered the A's for MLB.com since 2010.