Rosenthal, who had thrown once over the previous five days, has now had four 30-plus pitch outings in his 15 appearances in 2016. Last season, he reached 30 pitches once in 68 games. The Cardinals contend that the lack of sharpness -- Rosenthal has walked nine in six innings this month -- has something to do with the lack of consistent opportunities.
Rosenthal is on pace to appear in a modest 57 games after averaging 71 appearances over the last three seasons.
"It's just simply not enough work to stay sharp," Matheny said. "If we see him take long breaks and then be really sharp when he comes in, that's another story. But right now, he's just not quite where he wants to be. And sometimes the only way of fixing that is to throw."
So Matheny plans to have Rosenthal throw more often, even if that means risking not having him available in save situations. That's not a great concern, Matheny said, because of how well Seung Hwan Oh and Kevin Siegrist are pitching. Oh was a decorated closer in Asia before signing with the Cardinals in January, and Siegrist has served as a fill-in closer before.
"We have other guys who are throwing the ball well who will get the ball in those situations," Matheny said. "I think it's probably the priority at this point to get [Rosenthal] the amount of work that he needs until he is right, and then build on that confidence."
• Jhonny Peralta played another four innings for Class A Peoria (Ill.) on Saturday and went 0-for-2. Peralta, whose rehab assignment began on Friday, was to return to St. Louis on Sunday for an off-day and then head back out to another affiliate on Monday. Matheny did not specify where Peralta's next destination would be.
• Matt Holliday was missing from the Cardinals' lineup on Sunday as part of a pre-scheduled day off for the left fielder. Holliday entered the day hitless in his last 11 at-bats. With Holliday out, Stephen Piscotty slotted into the three-hole in the lineup. Piscotty, through Saturday, was batting .382 in May.
• The starting pitching matchups for the Cardinals' upcoming series against the Cubs have been set as such: Adam Wainwright vs. John Lackey on Monday, Michael Wacha vs. Jason Hammel on Tuesday and Carlos Martinez vs. Jake Arrieta on Wednesday.
Jenifer Langosch has covered the Cardinals for MLB.com since 2012, and previously covered the Pirates from 2007-11. Read her blog, follow her on Twitter, like her Facebook page and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.