Miami Marlins ace José Fernández was put on the 15-day disabled list Monday because of a sprained right elbow, spurring worries that his injury might be even more severe.
The 21-year-old Fernández was the NL Rookie of the Year last season. He is 4-2 with a 2.44 ERA in eight starts this year.
Several young pitchers have recently had elbow problems and needed Tommy John surgery. Matt Harvey, Stephen Strasburg and Patrick Corbin are among the All-Stars who have had the ligament transplant operation that can take 12 to 18 months for recovery.
"That's probably what everyone is going to talk about and continue to talk about," Marlins manager Mike Redmond said before Monday night's game against the Los Angeles Dodgers.
"We've protected him. We've been consistent in how we've used him, with his workload. We've given him extra days. That's a question I don't think anybody has the answer to."
Fernandez had been scheduled to start Wednesday at Dodger Stadium.
"He definitely wasn't going to throw (Sunday's scheduled bullpen session at San Diego) with a sore arm. We're going to take every precaution necessary. He said he felt discomfort. So immediately, we're getting him the treatment and the rest he needs," Redmond said.
"I think you're always concerned when you're talking about elbows. That's something we have to wait to find out. But I think we're always concerned about that with pitchers, especially," he said.
Fernández made 28 starts last year, going 12-6 with a major league-best .182 opponents' batting average. His 2.19 ERA was second in the majors behind three-time defending ERA champ Clayton Kershaw. Fernández struck out 187 in 172 2-3 innings.
"You see how much he means, so much to our team and our rotation and really all of baseball. He's been a dynamic player. He's been a huge lift and a huge spark for our team. We just hope everything goes well and he just has to take a little bit of a break," Redmond said.
The Marlins recalled left-hander Dan Jennings from Triple-A New Orleans. He made 79 relief appearances for the Marlins over the previous three seasons, going 3-5 with a 2.96 ERA.