ST. LOUIS -- As milepost games go, this one was a bad omen but perhaps an appropriate symbol.

The Cardinals stumbled badly in their 81st game of the 2010 season, seeing Chris Carpenter endure his worst start in five years in a 12-5 shellacking by the Brewers. For a team that manager Tony La Russa has admitted is limping to the All-Star break, ending the mathematical first half with such a performance was fitting if utterly frustrating.

Of greatest concern was Carpenter, who endured his worst start in five years, even though the defense behind him wasn't much better. Coming off of a start in which he was struck in the right forearm by a line drive, Carpenter's performance led to questions as to his physical well-being. He insisted that there were no issues, as did La Russa.

"I wouldn't go out there if I had an opportunity to hurt myself," Carpenter said. "My arm is fine."

Carpenter lasted three-plus innings, the third-shortest start of his St. Louis career. In each of the previous two starts in which Carpenter lasted three or fewer innings as a Cardinal, he was removed due to injury. He allowed eight runs, the second-highest total during his tenure as a Cardinal, on nine hits. Carpenter hit two batters, including one with the bases loaded. The last time he was reached for as many runs in a game was Sept. 23, 2005.

"Mechanically my delivery fell apart," he said. "I was pulling off balls, cutting balls off. My curveball [became terrible]. I kept battling, trying to come back, and I just wasn't able to get back on top of the ball and get my delivery under control. I didn't pitch well enough to give our team a chance. I've got to do a better job."

Yet in fairness, he also didn't get much help. In a four-run top of the third, the Cardinals defense made three blunders behind him.

With a runner on first and no out, Ryan Braun blooped a ball into right field. Nick Stavinoha couldn't catch it, but he threw to second base quickly enough to have a chance to retire the lead runner. Brendan Ryan leapt for the ball, however, and when he came down, he didn't tag the bag in time for the force out. The ball went as a hit.

Three batters later, Ryan made an ill-advised and poorly-executed throw home on Alcides Escobar's ground ball with runners on first and third, allowing a run to score and two men to advance. Ryan stood by his decision, saying only the throw was errant, but La Russa didn't see it the same way.

"He was deep enough, the runner runs good enough at third base, no," La Russa said. "It's a heroic type of play, but ... if you're coming in on the ball, and the runner is not as quick, maybe. But he was back, he didn't catch the ball coming in."

That line of thought was strengthened by the fact that the Cardinals already trailed, 3-0, at the time of the play. In a tie game or a one-run game, it might make more sense to take a risk to avoid another run. In a three-run game, the out is paramount.

"I thought the big play was, on our offense, was the ball Escobar hit to the shortstop and he decided to go home," Milwaukee manager Ken Macha said. "They weren't going to get two so it wasn't a bad play, but that kind of opened the inning up for us."

On a sacrifice fly one batter after that, Tyler Greene failed to cut off Randy Winn's throw, allowing a second run to score on the play.

None of which is to excuse Carpenter, who even with top-flight defense wouldn't have had a good game. He surrendered a solo homer before striking out the next three batters in the first, but in the second he got in trouble quickly. A single and a walk put two men on with one out, and with two out he hit opposing starter Manny Parra. Another hit batsman brought in the second Milwaukee run, and it was clear Carpenter didn't have his best command.

He trudged his way through the ugly third, and came out for the fourth but didn't get an out. Three singles and a walk chased him as Dennys Reyes came on.

"When you put your team down 8-0 in three innings, it's not going to give them a chance to [win] or give them a whole lot of hope," he said. "I didn't pitch well enough to give our team a chance to win."

Jason LaRue and Albert Pujols homered for the Cardinals in a three-run fifth, and Greene added a two-run triple in the sixth. The Cards' comeback, such as it was, magnified a frustrating bottom of the third when they loaded the bases with no outs and didn't score. A couple of runs at that point might have cast the rest of the game in a different light, but it didn't happen.

St. Louis remained 1 1/2 games behind the Reds in the National League Central.