[Peter_Spaeth]

We need a metric that is independent of fielding, team strength, opposing team strength, stadium, and even result (not just of the game but of the pitch itself, after all you could throw a fabulous pitch and Hank Aaron might still hit it out). We need to focus solely on the pitch itself -- the quality of each pitch a pitcher threw during his career, with some appropriate mechanism to average or to assign relative weights to different ones. Any other metric has too many confounding variables.