CHICAGO -- Any question about whether Joel Zumaya would pitch again this season was answered Thursday, when the Tigers reliever was diagnosed with a stress fracture in his right shoulder.

It's the latest piece of bad medical news in what has been two rough years for Detroit's hard-throwing right-hander ever since he burst onto the big league scene in 2006.

Zumaya missed the first 2 1/2 months of the season after surgery last fall to repair the AC joint in his throwing shoulder. He made 21 appearances out of the bullpen with mixed results before the team decided to rest him in mid-August with what was termed a sore right shoulder.

Zumaya had been on a throwing program to try to ease the shoulder back to full strength. However, the 23-year-old woke up Thursday with discomfort in the shoulder, according to head athletic trainer Kevin Rand. Zumaya was sent to team physician Stephen Lemos, who diagnosed the stress fracture of the right coracoid, a bone in the front of the shoulder from which several muscles attach.

It's a rare injury for a baseball player, and it's uncertain whether it's related to the equally rare shoulder surgery from last fall. Zumaya also missed half of last season after rupturing a tendon in his right middle finger while warming up in the bullpen during a game at Kansas City, but that was a different injury.

Whatever the case, this latest injury was not sudden.

"It's something that happened over the course of time from throwing," Rand said.

Likewise, it will not be a quick healing process. The rehab timeframe calls for Zumaya to avoid any baseball activity for six to eight weeks before starting a rehab program. That seemingly would put him on track to be ready for next spring.

"He's got to let it heal," Rand said.

Zumaya's season ends with an 0-2 record and a 3.47 ERA. He struck out 22 and walked 22 while allowing 24 hits over 23 1/3 innings.

When healthy, Zumaya is a major presence in the late innings for the Tigers. He was seen as a potential closer at the end of last season, when the team wasn't sure whether free agent Todd Jones would re-sign. Zumaya's shoulder injury during an accident at home in San Diego ensured Jones would be the unquestioned closer, but Jones' own injury woes this year have left Fernando Rodney in the role for the last two months.