PHILADELPHIA -- Mark Kotsay compared Luis Medina to one of the best starting pitchers in baseball on Saturday. It was the kind of comparison a manager never wants to make about a young starting pitcher.

The Athletics placed Medina on the 15-day injured list with a right elbow sprain, with Kotsay adding that he expects the 25-year-old flamethrower to miss “significant” time.

"I think it was kind of similar to [Jacob] deGrom with the UCL," Kotsay said before Saturday’s game against the Phillies. "Really unfortunate for Luis. You can never tell when this type of injury occurs. He was still throwing 99 mph."

Medina’s velocity was down during his last start, in which he allowed six runs and struck out seven over five-plus innings in Boston, but his fastball touched triple digits in his final inning. It was unclear how long Medina would be out for, but Kotsay did not rule out surgery.

“We’ll know for sure after the break but we’ll let him go home and have some days with his family,” Kotsay said, noting they would likely get a second opinion.

Medina, who started the year on the injured list with a right knee sprain, was 2-4 with a 5.18 ERA over eight starts.

The injury offered a sobering reminder of the risks of increased velocity, a day after All-Star closer Mason Miller touched 103.7 mph with his fastball.

“Nowadays it’s not ‘if,’ it’s more likely ‘when’ it’s going to happen,” Kotsay said of arm injuries. “That’s the way the game is going."

As for the future of the rotation, Kotsay said the focus was getting through the next two days, then reassessing after the break. He mentioned Nick Blackburn and Ross Stripling, both of whom are returning from injuries themselves, as well as Osvaldo Bido, who shut out the Phillies over three innings of long relief on Friday.

“[Bido’s] a guy we targeted this offseason,” Kotsay said. “We gave him a Major League deal and felt confident he could help us this year in some role, whether that’s long relief or the rotation. Yesterday he threw pretty well. He’s done a nice job. We’re fortunate that we have some good options.”