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5/18/2013 6:54 P.M. ET

Mujica bringing stability in newfound closer role

Before this season, Edward Mujica had saved just four games. He was an average middle reliever who had bounced around to three teams in five years before arriving in St. Louis last season via a trade with the Marlins.

But with Jason Motte sidelined after Tommy John surgery and Mitchell Boggs struggling, Mujica was thrust into unfamiliar territory as the Cardinals' closer, and he is bringing stability to a beleaguered bullpen.

Since assuming the closer role from Boggs, Mujica has converted all 12 of his save opportunities and has allowed just two earned runs. He also hasn't allowed a batter to reach base in his last five games.

"It's been crazy for me," Mujica said. "When I started the year, they told me I was gonna be in the seventh inning, but, you know, with the whole situation with the bullpen in the beginning, they gave me the ball and I'm just enjoying this time right now as the closer."

Among Mujica's 12 saves, six came in games where the 29-year-old right-hander took the mound in the ninth with just a one-run cushion on the board.

"He's been big, and obviously that's an understatement," said manager Mike Matheny after Friday's 7-6 win over Milwaukee. "He and Yadi are working well together in those tight situations, and I don't think he really addresses his pitch selection or any batters any different with a three-run lead than he does with a one-run lead."

Boggs rejoins Cards' bullpen from Triple-A

ST. LOUIS -- Mitchell Boggs will rejoin the Cardinals' bullpen on Sunday, taking the roster spot that opened when the team placed Jaime Garcia on the 15-day disabled list.

Boggs has been in Triple-A Memphis searching for his mechanics and his confidence since a May 3 demotion. The right-hander, who opened the season as the Cardinals' closer, left the big league team after allowing 17 hits, 12 walks and 15 earned runs in 10 2/3 innings.

Boggs began his stint in Memphis with five scoreless innings before being knocked around for three runs while recording only one out on Thursday. He walked three and allowed two hits in that appearance.

"With the exception of his last outing, he's been throwing the ball real well," general manager John Mozeliak said. "Given that Jaime is not going to continue, it doesn't make any sense not to make a roster move. And the fact that [Boggs] was making positive progression, he was a natural choice."

The Cardinals' bullpen will lose another member by Wednesday since the Cardinals need to address the hole in the rotation. One of the current relievers may be thrust into a starting role, or one will be sent down in order to allow a roster spot to open for someone else.

Carpenter throws extended bullpen session

ST. LOUIS -- Earlier this week, Chris Carpenter jokingly noted that he wasn't sure where he would be needed if he is able to return and pitch for the Cardinals this season. Now, with Jaime Garcia sidelined indefinitely with a shoulder injury, Carpenter's comeback attempt takes on some added significance.

Carpenter took another small step toward returning on Saturday, when he threw an extended bullpen session shortly before the Cardinals took the field for batting practice. He threw more pitches than he did on Wednesday and took breaks in between sets to simulate getting up and down during a game.

"He's in phenomenal shape, we all know that," said manager Mike Matheny, who watched part of the session. "He's a tireless worker and you could see that he was right at the point he wanted to be which was tired and see how he could still execute his pitches."

Carpenter is expected to throw another short side session on Monday followed by a longer one on Thursday. General manager John Mozeliak said that the club has already mapped out a plan beyond that, but he did not divulge any details.

"He's progressing, which is encouraging, especially since we've lost another starter," Mozeliak said. "When we were asking these questions [about where he would fit on club] two weeks ago, it was, 'Whose spot is he going to take?' Well now it's like, 'Get healthy faster.'"

Worth noting

• Top prospect Oscar Taveras has still not resumed playing since rolling his right ankle in a Triple-A game last Sunday. Taveras, ranked by MLB.com as baseball's third-best prospect, was hitting .317 with a .351 on-base percentage at the time of the injury.

• Matt Adams was back in the Cardinals' lineup on Saturday, making just his second start since coming off the disabled list on May 7. In order to get Adams a start, manager Mike Matheny sat right fielder Carlos Beltran. Beltan entered the day 8-for-28 on this homestand.

Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. Chad Thornburg is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.