Tyler Kolek, the Marlins' No. 1 prospect, had Tommy John surgery on Wednesday.
The surgery, which has not been confirmed by the club, was performed by Dr. David Altchek.
Kolek experienced elbow discomfort at the end of what had been an encouraging Spring Training for the No. 2 pick in the 2014 Draft, and he had an MRI to determine the extent of the injury. He met with the team doctor last week, but the results were inconclusive, so Kolek received a third opinion before opting to have the surgery.
The Marlins had been weighing whether to start Kolek off at Class A Advanced Jupiter or Class A Greensboro, where he made 25 starts and posted a 4.56 ERA in 2015.
From Shepherd, Texas, Kolek had his fastball clocked at 102 mph as a prep standout. During his first full season, he struggled with command and in repeating his delivery. Kolek has made 34 Minor League appearances (33 starts), logging 130 2/3 innings. He's struck out 99 and walked 74.