Nerfherders wrote:4. Stuff. This is easy enough to evaluate. It's simply K rate vs. ERA. Closing is all about NOT putting the ball in play. K's are gold for relievers.
I'd probably go a little deeper here and use some projected era and whip numbers. Here's an example of each:
DICE = 3.00 + ((13 * HR + 3 * BB&HBP - 2 * K) / IP)
pWhip = ((0.4 * (3 * IP - K)) + BB + HR) / IP
These numbers are based completely on striking out batters without giving up walks and home runs. While most closers get good numbers by striking out a lot of hitters you can be successful as a closer by walking very few batters and giving up almost no home runs as well. The lower these numbers are the better chance for success as a closer and as a pitcher in general. But these are crucial for a closer because while a SP can give up a run every other inning and get by a closer really can not.