Fernandez had at least one MRI on Monday, and the revelation of a sprain suggests the ligament is involved, as Will Carroll (@injuryexpert) of Bleacher Report said. Damage to the ulnar collateral ligament could mean Tommy John surgery, and a year recovery. Marlins manager Mike Redmond acknowledged to reporters that's always a concern when this type of injury occurs. The South Florida Sun-Sentinel reported the Marlins are expecting season-ending elbow surgery.
Fernandez is said to have experienced discomfort in at least the last start, a rare bad outing when he allowed six runs (five earned) in five innings at San Diego in a 10-1 defeat to the Padres. Fernandez was apparently trying to tough it out, but upon revealing his discomfort was advised to be examined in Los Angeles on Monday.
Another potential sign of trouble was dipping velocity in his last start or two.
There's been something of an epidemic of elbow injuries and surgeries this season, especially among young pitchers.
Clark Spencer of the Miami Herald (@clarkspencer) first reported Fernandez needed an MRI, and Ken Rosenthal (@Ken_Rosenthal) reported he'd be going on the 15-day disabled list, which he did later Monday afternoon.
Fernandez is said to be heading back to Miami now, presumably to see Marlins doctors as they figure out how to fix one of the brightest young stars in the game. Fernandez, 21, is 4-2 with a 2.44 ERA, and helped lead the Marlins to a nice start this season.