But the Cardinals aren't concerned with numbers. Instead, their immediate priority is evaluating how Rosenthal bounces back after each outing.
"I would say that he's one of the physically strongest guys that we have," Matheny said. "The way that he has worked has prepared him for this. We'll continue to watch him. Any signs that it's affecting him, we'll change course. But right now, he's doing a great job. He prepared to be a starter this year. He prepared for 200 innings. We're not going to get him that, but we're going to get him an opportunity to help us win."
The Cardinals have leaned heavily on Rosenthal so far this season because of how reliable he has become as the team's eighth-inning setup man. He ranks second in the NL with 13 holds and tops NL relievers with 32 strikeouts. His 33 percent swing-and-miss number is the best in the league.
"I feel like it's been good for me to get out there and pitch frequently," Rosenthal said on Monday. "Obviously, having a chance to contribute to a lot of team wins is fun, too. I feel like I have learned a lot by doing that. I feel good so far physically."
Rosenthal said he has adapted his workout routine as a way to compensate for the workload. He has cut down on the time he spends in the weight room and is more concerned with maintaining muscle than he is focused on putting more on, as he did this offseason. Rosenthal's objective in his workouts now is to do enough to get loose, but not so much that he tires.
"Because I've never done this type of role before, I'm still trying to get a feel for it," Rosenthal said. "Right now, I feel good. And hopefully I'll answer that question the same in October. I'm expecting that work to pay off."
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.