"We just need to figure out a way to get him right and figure out how to get him to the point of being the pitcher that he's been the last few years," Matheny said before Saturday's game in Seattle. "Right now, the ninth inning is a tough ask to do that. We'll continue to watch, but right now we're going to wait and see if we can get him into some spots to get him in that good place."
Though he converted 11 of his first 12 save opportunities this season, Rosenthal has made too many of his appearances too eventful. Walks have regularly complicated innings for the righty, who has averaged 21 pitches per inning this season. His percentage of first-pitch strikes sits at 61 percent.
Matheny described Rosenthal as "disappointed" when learning of the role change.
"He wears it very personally that he's not been able to do what he wants to do," Matheny said. "It stings. That's such a volatile spot. You come in there, and you're a hero or a goat. It's one of the two. It's never easy being that goat when you know he physically feels good and is not getting the results he wants. We have to tinker a little bit."
Matheny has not named a replacement closer, but said he will instead consider Seung Hwan Oh, Kevin Siegrist and Jonathan Broxton as options for future save situations.
Though all three have saved games before, Oh is the most decorated closer of the bunch. Before signing with the Cardinals over the winter, Oh compiled 357 career saves pitching in Korea and Japan. He became the fastest pitcher to reach 100 saves in Korean history and is still the league's all-time saves leader.
Oh currently ranks among the top eight National League relievers in ERA (1.66), strikeouts (51), Holds (14) and WHIP (0.79).
Broxton was an All-Star closer for the Dodgers in 2009 and 2010. He has compiled 118 career saves, though none since 2014.
Siegrist is the only Cardinals reliever besides Rosenthal to close a game this season. He has tallied seven career saves and entered Saturday with a season ERA of 2.79.
Fantasy spin | Fred Zinkie (@FredZinkieMLB)
With a 5.63 ERA and a 2.04 WHIP this season -- plus control woes dating back to 2014 -- Rosenthal could no longer be trusted in the closer's role. Most mixed-league owners should drop the righty this weekend, with Oh, Siegrist and Broxton now candidates to take the ninth-inning helm. Given his dominant ratios this season and 357 career saves as a professional overseas, Oh should be considered the favorite to earn saves. He could achieve top-tier status, if given an extended chance.
Jenifer Langosch has covered the Cardinals for MLB.com since 2012,
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Langosch for Cardinals.com and listen to her podcast. This story was not subject to the approval of Major League Baseball or its clubs.