PITCHf/x: the gift that keeps on giving. Based on the Gameday reporting of balls in the dirt, Dan Turkenkopf ran a 2007 analysis of how often regular catchers are able to block bad pitches. The league average backstop last year had a block rate of 86%, but there was quite a spread between Mike Redmond (best) and Ivan Rodriguez (worst). Kenji Johjima comes out at 83% - ~2.4 runs below average - which serves to support the notion that he stabs at pitches too much instead of shifting his body over.
Interesting stuff. I won't go so far as to call it groundbreaking, since it's only one year's worth of data and there are some valid concerns regarding the methodology, but it's a solid first attempt towards the proper analysis of something that before was based almost entirely on observation.