"I can't confirm any type of injury at this point because he hasn't been seen [by doctors]," Ricco said. "He came out of the game and we put him on the DL."
Hefner left after just one inning in his start with Class A St. Lucie on Wednesday. He had Tommy John surgery last year because of a partially torn MCL in his right arm, and it's unclear if the injuries are related.
Erik Bacharach is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.