"We were looking for a huge lift from him, and so far we've gotten it," said manager Tony La Russa. "So this is definitely not good news to see him leave the game. Maybe he'll catch a break, and we'll catch a break."
The right-hander, returning from Tommy John reconstructive elbow surgery, allowed a double to Alfonso Soriano to open the sixth. He got Kosuke Fukudome out on a grounder back to the mound, but Derrek Lee singled Soriano home for a 2-0 Cubs lead. Aramis Ramirez walked, bringing up Jim Edmonds.
On his first pitch to Edmonds, a strike, Carpenter felt pain in his triceps. Carpenter misfired on the next pitch to his former teammate and summoned catcher Yadier Molina to the mound. Shortly thereafter, Carpenter and Molina were joined by La Russa and head athletic trainer Barry Weinberg, and Carpenter was immediately lifted.
"I threw that first pitch to Jimmy and I felt something down in my triceps," Carpenter said. "I tried to throw the next pitch and felt it again. So I decided to make the call."
Unfortunately, the injury was only the start of an ugly inning. Some shaky defense and iffy relief work compounded the troubles before the frame was over.
Ron Villone, who relieved Carpenter, induced a grounder to second that could have ended the inning. But Adam Kennedy lifted his glove too soon, and the ball scooted into the outfield, bringing home a run. Mark DeRosa then singled against Brad Thompson, on a ball that Cesar Izturis at least had a chance to keep in the infield, if not make a play on.
Three more singles made it a five-run inning, with the Cards only bailed out by a pair of overaggressive baserunning plays by Chicago.
"I just didn't play it good," Kennedy said. "They took advantage of that one mistake I made and really poured it on."
Meanwhile, Carpenter's opposite number, Ryan Dempster, held the Cardinals down despite frequently finding himself in trouble. He kept St. Louis off the board until the seventh, when Joe Mather's RBI double ended the shutout bid and chased Dempster. Albert Pujols knocked a double that scored Mather, but it was far from enough.
That's partly because of a glaring miss in the fifth inning that left the Cardinals shaking their heads. Schumaker placed a single perfectly up the middle with one out, and Mather worked an outstanding at-bat to draw a walk. The Cards had their two sluggers coming to the plate with two men on.
But Pujols popped up to second base for out No. 2. Ryan Ludwick then hit a comebacker to Dempster, who fielded it cleanly and flipped to first base for the final out of the inning.
"He's a strike-thrower," Skip Schumaker said of Dempster. "We knew that coming in. he can throw three pitches for strikes, and he's got really good control of all three of his pitches. He's a good pitcher, first time we've seen him this year. There's a reason he's got 13 wins. He throws strikes and lets his guys play behind him."
The Cardinals trail the first-place Cubs by seven games in the National League Central with six head-to-head meetings left on the schedule. Perhaps more distressingly, they now stand three games behind the Brewers for the NL Wild Card lead.