Carpenter, who is dealing with a muscle strain in the back of his right shoulder, ends the season with four appearances, three starts, covering 15 1/3 innings. He has pitched in five Major League games since the end of the 2006 World Series.
"I truly don't even know what to say," Carpenter said on Friday night. "I have no explanation. I can't explain it. The only feeling I had is that I'm disappointed and frustrated and everything else you can think of."
The club announced that in addition to a previously diagnosed strain of the teres major muscle, Carpenter has "nerve irritation" in his shoulder. According to a release from the Cardinals, the nerve condition "is not related to [Carpenter's] ligament reconstructive surgery" or to a nerve problem that sidelined Carpenter in 2004.
General manager John Mozeliak and manager Tony La Russa expressed optimism that Carpenter would be ready to go for the start of the 2009 season. Still, the nerve condition certainly presents a new wrinkle to what otherwise looked like a relatively straightforward situation.
"There's a nerve issue that is a concern, but I don't get the feeling that in '09 it should be a huge issue," Mozeliak said.
The right-hander started Opening Night in 2007, then came down with an elbow injury. He underwent Tommy John reconstructive elbow surgery in July of last year, sidelining him until late July 2008.
Upon his return, Carpenter pitched quite well. In his three starts, beginning on July 30 in Atlanta, he posted a 1.88 ERA. However, he left his third start, on Aug. 10 in Chicago, with the shoulder injury and was placed on the disabled list.
When Carpenter returned to the active roster, he was sent to the bullpen with the hope that he could make a few relief appearances to build his confidence and ease his mind going into 2009 -- as well as hopefully help the ballclub hold down some leads in the late innings.
Yet Carpenter made only one relief appearance, on Sept. 2 against the Diamondbacks. He did not recover from that game as hoped, and after warming up on Sept. 5 at home, he has not been available since.
Matthew Leach is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.