Flaherty was called up Saturday in order to make his scheduled start against the Pirates.
Flaherty is needed in the Cardinals' rotation with Adam Wainwright (elbow) on the disabled list. It's unclear how many starts he'll get, as there haven't been any reports that Wainwright's issue is particularly serious. Flaherty made one start for the Cardinals earlier this year, allowing one run on six hits and a walk over five innings, striking out nine.