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08/02/10 7:55 PM ET

Robertson gives Cards' 'pen depth

ST. LOUIS -- Left-hander Nate Robertson, who signed a Minor League deal with the Cardinals on Monday, will begin working his way back at Triple-A Memphis. Robertson started 18 games for the Marlins this season, and last started on July 20. He was released by Florida on July 27.

Robertson struggled this season with Florida, posting a 5.47 ERA and 1.495 WHIP in 19 appearances, 18 of them starts.

Although it is doubtful the Cardinals would call Robertson up as a starter with the recent addition of Jake Westbrook, and Kyle Lohse close to returning, he could be used as a left-handed specialist out of the bullpen. Currently, lefty reliever Dennys Reyes has posted a respectable 3.00 ERA this season, but has a 1.333 WHIP and is walking 5.1 batters per nine innings. After starting the season with a 0.54 ERA in 25 games, Reyes has been shelled for a 6.39 ERA in his past 22 games.

Cardinals manager Tony La Russa dismissed the notion of inserting Robertson into the bullpen, however.

"Well, he is really not a left-handed reliever, that is the one thing," La Russa said. "You know, he has made a career pitching against right-handed lineups."

Robertson has had substantially more success versus lefties in his career, though. Right-handed hitters have posted a career .829 OPS, while left-sided hitters are significantly lower with a career .694 OPS.

La Russa defends Westbrook deal

ST. LOUIS -- One the eve of Jake Westbrook's first start with the Cardinals, manager Tony La Russa vehemently defended the trade that sent right fielder Ryan Ludwick away to bring in Westbrook.

A position stated by general manager John Mozeliak earlier in the week, La Russa said adding another starting pitcher to complement the dominant trio of Adam Wainwright, Chris Carpenter and Jaime Garcia was the organization's first priority to reach the playoffs.

"We weren't going to get to October without a pitcher," La Russa said. "For whatever my opinion is worth. We weren't going to get there. This gives us a chance."

Critics of the deal have pointed that the Cardinals are second in the National League in team ERA and have been consistently in the bottom half of the NL in runs scored, currently ranked eighth.

Ludwick was hitting .281 with a .344 on-base percentage and .484 slugging percentage with 11 home runs in 77 games when he was traded. Jon Jay has started his Major League career on fire, currently batting .378/.427/.571.

At the Whitey Herzog uniform number retirement ceremony Saturday, Mozeliak received a smattering of boos from the fans when he was announced.

"We would love to have him here. Believe me, I wish we could have done it with him here. But the choice came down to you need a pitcher. After all the efforts, this is a guy we wanted and Luddy had to be a part of it. So arguably we have got guys like [Allen] Craig and [Nick] Stavinoha and Jay, and we got potential to have some offense here."

Cards' Penny continues to play catch

ST. LOUIS -- With Jake Westbrook joining the rotation and Kyle Lohse likely to rejoin in the next two weeks, the return of starting pitcher Brad Penny has been pushed into the background of Cardinals news. But according to manager Tony La Russa on Monday and Penny himself, the season is not yet done for the big right-hander.

Penny continues to play catch each day, but no bullpen has been scheduled in the near future.

Penny has been on the disabled list with a strain lat since May 21. Originally, the injury was expected to take around 2-3 weeks to heal.

"I hope so," Penny responded when asked if he will return this season. "I'll do everything I can. But like I said, I've got to test it."

Worth noting

Brendan Ryan is hitting .500 over his last seven games, collecting multiple hits in every game but one. ... Cardinals starters Adam Wainwright and Jeff Suppan have driven in the game-winning run in consecutive nights for the Cardinals. Monday's starter Jake Westbrook is 2-for-14 (.143) lifetime at the plate. ... Albert Pujols hasn't walked in six games, his longest streak without taking a base on balls since 2008.

Michael Bleach is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.