David Gassko at Book of Odds has a great analysis on the continuity of closers from season to season. Essentially, for most teams, there isn’t any.
I found this link in a post at Another Cubs Blog. Author mb21 cuts to the chase:
There’s no such thing as a closer of the future.
In Moneyball Michael Lewis noted Billy Beane’s success in keeping closers on a budget. He avoided paying for the successful and generally (barring injuries and Octavio Dotel) had few problems bringing up new ones.
A corollary, I suspect, is that there’s no special value in college closers.