Workload concerns don't just circle Rosenthal, either. Matheny has been bullish in riding the arms of his most trusted three relievers -- Rosenthal, Carlos Martinez and Kevin Siegrist -- and that could present potential fatigue concerns later this season if Matheny doesn't find other relievers to use.
That's one of the reasons why Jason Motte's return -- he came off the disabled list on Tuesday -- could be especially imperative.
"We've had a lot of close games in a short amount of time here, and that puts a lot of weight on them," Matheny said of his late-inning trio. "With Motte being able to come back here, a guy who knows how to pitch in big innings, and [Pat] Neshek certainly has the ability to pitch in those games as well and take some of the pressure off them at times."
The pushing of setup men Siegrist and Martinez has led them to each pitch in half of the team's 44 games through the weekend. Those 22 appearances rank sixth-most in the National League and puts the two young pitchers on pace for 81 outings. That is a total that no NL reliever reached last season.
Martinez, with 23 innings entering Tuesday, had the seventh-highest innings total among NL relievers. Rosenthal wasn't far behind him at 21 2/3.
"I haven't made it any secret about the fact that the only way we were going to be able to get through going through a tough time is pushing," Matheny said. "We've been pushing. Sometimes that's pushing arms. Sometimes that's pushing position players. But we're just trying to find a way to stay in this and keep fighting."
In the past week, Rosenthal had been used in five games, Martinez in four and Siegrist three times. Matheny made Siegrist hands-off for a period last week because of concerns about overuse.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. Alex Halsted is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.