There isn’t any reason to freak out, but a little elbow stiffness isn’t a good thing for a pitcher with Isringhausen’s history. He was a good pitcher only in the last month of last season. And the Cards have at least two other pitchers (Veres and Kline) who can close games. And Tony La Russa likes unusual usage patterns.
All are good reasons not to pay a premium to make Isringhausen your closer this year.