(Chris Lee/AP)

When the Cardinals set their lineup for the National League division series against the Nationals, Manager Mike Matheny made the decision to include only one left-handed reliever in the mix – Marc Rzepczynski.

It’s a rather risky move. Having only one lefty in the bullpen magnifies every decision Matheny makes when deciding when to use him, for how long and against which batters during this series.  And as Game 1 showed, in certain situations it gives Nationals manager Davey Johnson the opportunity to control matchups.

“Hopefully it’s a big issue for them,” Nationals first baseman Adam LaRoche said. “That’s the goal is to get into the bullpen. So if we can get in there early and make them make a decision when they want to use him, then they have pretty much got either myself or Bryce [Harper]. To not have another one backing them up I think can help us out.”

Sunday, the Cardinals’ move to Rzepczynski in the eighth wound up turning the game in Washington’s favor. The Nationals were set to pinch-hit left-handed Chad Tracy against Mitchell Boggs, prompting Matheny to go with Rzepczynski. Rather than leave Tracy in to face Rzepczynski, Johnson smartly swapped in right-handed rookie Tyler Moore. He hit a flare down the first base line that scored a pair of runs to give the Nationals a 3-2 lead they didn’t relinquish.

“I replayed that in my head many times,” Matheny said Monday of the decision to swap pitchers in that moment. “It’s easy to sit back and look at what if I would have done this, that or the other and you can pretty much drive yourself crazy in this business if you do that enough.”

The Cardinals used additional lefties throughout the season, but once they picked up Edward Mujica from Miami at the trade deadline the role of a left-handed reliever diminished significantly.  Instead, Matheny leaned heavily on using Mujica, Boggs and closer Jason Motte in the final three innings of a game regardless of the hitter they faced. It wouldn’t be surprising if the Cardinals opt for that strategy at some point during this series as well.

While the trio worked well for the Cardinals in the regular season, the recipe may have also reflected on Rzepczynski’s struggles. He lost the feel for his slider and rough outings kept piling up along with the bad luck. Over 46.2 innings in the regular season, Rzepczynski had allowed 22 earned runs and 46 hits.

All that considered, though, there wasn’t a large discrepancy in how right-handed batters (.259) fared against him as opposed to left-handers (.255). Matheny showed his confidence in Rzepczynski when he elected to make him the lone left-hander in the bullpen during the NLDS.

It was a move Matheny based on Rzepczynski’s experience in the postseason – he pitched 8 1/3 innings during the Cardinals’ 2011 run to the World Series – and the fact that he improved late in the year despite being used far less often.  That faith in Rzepczynski didn’t make the pitcher feel any better after Cardinals’ 3-2 loss in Game 1 though.

“You’ve got to tip your cap to him. He hit a pitch that most people don’t even swing at, for the most part,” Rzepczynski said of the 2-2 pitch Moore hit that was outside and off the plate. “In the same sense, I’m upset because it cost us the game.”

Asked how he helps his only lefty reliever bounce back from allowing that hit, Matheny reiterated his confidence in Rzepczynski.

“He’s been on the bad side – I’m not a real big fan of the term luck, but if there is such a thing, he’s had a lot of bad luck this year and things that could go wrong, balls just bleeding in,” Matheny said, praising Rzepczynski’s resiliency. “I like the way he’s been throwing the ball and we need him….We know he’s going to be able to come through big for us again, and just get ready for it and put this stuff behind us.”