Miami Marlins top prospect Robby Snelling's major league debut proved to be a painful one.

Snelling had allowed three runs on five hits and four walks over five innings on May 8, striking out a pair of batters. However, he had discomfort in his left arm after that outing. Craig Mish from SportsGrid reported that Snelling will undergo Tommy John surgery after being diagnosed with a sprained ulnar collateral ligament.

Given the timing of his surgery, it is uncertain as to when Snelling will return. He could return in time for the second half of the 2027 season, although, if the Marlins are out of the playoff hunt at that time, they could opt to be cautious and look for Snelling to be ready in 2028.

Robby Snelling a significant loss for Miami Marlins

Snelling had been ranked as the Marlins' second-best prospect, and the 39th-best prospect in baseball, by MLB.com to begin the season. He had been lauded for his bulldog mentality, attacking opposing hitters with his mid-90s fastball and sweeper that showed signs of being plus offerings. 

There is one silver lining for Snelling. As the injury occurred while he was on the major league roster, he will receive the major league minimum while rehabbing. Otherwise, if he had been placed on the injured list prior to his promotion, he would have only received his minor league salary without accruing service time.

In the short term, the Marlins are in a difficult spot to fill the rotation. Braxton Garrett had struggled in his first two major league outings and was sent back to Triple-A. Depth pieces such as Dax Fulton and Ryan Gusto have been middling at best. One of those two may get the first chance, with Garrett as an option once his window to be called back up passes.