But the Cardinals weren't looking for another impact bat in the way they had been back in 2009, when Matt Holliday was added at the Trade Deadline. There was no rotation issue to address in the way that there was in '11, when Edwin Jackson was among the Cardinals' July acquisitions.
Yet, fourth months into the 2012 season, the Cardinals were still unable to solve the seventh inning with consistency. The team was 50-2 when carrying a lead into the eighth, but the bridge needed to get there was, at best, unstable.
Mujica proved to be the missing plank, a piece that, when added to the bullpen mix, helped everything to connect. He wasn't a half-season bandage, either, and his return has the Cardinals seemingly in a much less precarious spot than the club was a year ago, when it had several bullpen unknowns.
"The addition of Mujica last year at the All-Star break gave it more form," closer Jason Motte said of the 'pen. "I think going into last year, we had some questions. We had a bunch of guys who didn't know what their roles were going to be."
The 2012 season settled many of those issues. Motte proved that he can handle full-time duty as a closer. Mitchell Boggs earned the eighth inning with his dominance. Once Mujica was inserted to precede the late-inning pair, the Cardinals' bullpen had definition.
Manager Mike Matheny has no intention of fiddling with a sequence that worked so well late last season, though he will insert a new wrinkle into the late-inning equation. The Cardinals' decision to commit $7 million over a three-year period to Randy Choate drew the veteran lefty to St. Louis.
Choate's role can be narrowly defined -- he'll serve as a lefty specialist -- but Choate's one- or two-batter appearances will come at critical times.
"He's a guy that's going to be specifically effective against lefties, and we have to be real smart with how we use him and put him in positions to succeed," Matheny said. "There are some lefties, especially in our division, where we could use a guy like that."
Not only did the Cardinals lack a left-handed specialist in 2012, but the club struggled, in general, to find two lefties who could come through with consistency. Marc Rzepczynski was the only left-handed reliever to remain on the club from Opening Day until finish, and even his season was hardly up to expectation.
Rzepczynski was particularly hit by adversity in May and June, and his numbers never recovered. The uncertainty of Rzepczynski's command and the absence of other left-handed options often left the Cardinals struggling to find the right spots for the lefty. Choate's arrival will eliminate part of that dynamic, freeing up Rzepczynski to help the Cardinals in the middle innings.
"There were times when we didn't have any help for [Rzepczynski]," Matheny said. "His role was pretty undefined. It was a different-looking bullpen. But I think Randy brings a different flair this year. I am counting on it being an asset that does work for [Rzepczynski]."
The Cardinals' decision to tender a contract to the arbitration-eligible Rzepczynski this offseason confirmed their plans to include him in the bullpen again this year.
"I look back on it and I know I could have improved on a lot of things," Rzepczynski said of the 2012 season, which he finished with a 4.24 ERA. "That's why this [offseason], I didn't waste any time. I got into the gym a week and a half after I got home. That's how dedicated I am to proving how good I was in '11 and getting back to where I was."
The Cardinals have a plethora of candidates for the final two bullpen spots, though Fernando Salas is a favorite to claim one of the openings. Despite his own 2012 inconsistencies -- some of which could be explained by a kidney stone issue early in the season -- Salas has proven himself a capable Major League reliever in the past.
Salas saved 24 games and posted a 2.28 ERA in 68 appearances back in 2011. His workload that season (75 innings) is another factor that some believe led to the inconsistent results in '12.
The way the Cardinals complete their bullpen will have a lot to do with how the rotation fills out. Three candidates -- Joe Kelly, Trevor Rosenthal and Shelby Miller -- for the final starting job all spent time in the Cardinals' bullpen last season, and each thrived as members of the 'pen during the postseason.
The club will have to weigh the instant benefit of having one of the three on the Major League club as a reliever against the potential long-term payoff of keeping them extended as starters, even if they are at Triple-A.
There is always the opportunity, too, for someone else to surprise. Victor Marte, Eduardo Sanchez and Maikel Cleto are among those in camp who spent time on the Cardinals' big league roster last season.
"We still have a lot of pieces that are still trying to be figured out," Matheny said. "I do believe there are more options than what I thought we had a year ago. But there are still some pieces that are going to be interchangeable at this point. We've just got to wait and see how that all plays out."