Joel Zumaya hasn't played a full (regular) season since his rookie campaign in 2006, but even then he missed time in the playoffs due to injury. It all started with an alleged Guitar Hero wrist injury, which forced him to miss the ALCS.
The injuries have been more serious and plentiful since then.
In May of the 2007 season, Zumaya ruptured a tendon in his throwing hand forcing him to miss 12 weeks. During the offseason before the 2008 season, a 50-60 pound box reportedly fell on his shoulder while trying to help his family move things following the San Diego wildfires. It separated his shoulder and landed him on the DL to start the season. In 2009, Zumaya missed time due to the same shoulder causing him severe problems. He ultimately had surgery on it in August 2009 and missed the rest of the season. He returned healthy in 2010, and looked to be back to his 2006 self, but at the end of June he broke his elbow in Minnesota and was placed on the DL for the rest of the year.
All signs point to Zumaya being healthy again by Spring Training 2011, but that's not enough anymore. As Jim Leyland points out, the key will be keeping him healthy, somehow:
"The reports are that he's going to come into spring training and be ready to go," manager Jim Leyland said Wednesday at the winter meetings. "The problem is keeping him healthy. We haven't been able to do that. It's been freak things."
If Zumaya can remain healthy for an entire season, obviously he's a huge asset to the bullpen. A healthy Joel Zumaya makes the Tigers bullpen (arguably) one of the best in baseball, as he'd be joining three other solid, hard-throwing righties for late-inning duties. At this point, unfortunately, it's more of a "I'll believe it when I see it" sort of thing with Zumaya's health status than anything else.
Even Zumaya's already looking ahead beyond his next injury, as he hasn't been shy about stating that another injury could end his career and force him to look for employment elsewhere.