Wednesday, July 05, 2006

Better Defense Through Bruising

Sean Forman, master of Baseball-Reference, put together an interesting presentation for the just-completed SABR convention. He looked at all catcher seasons since 1957 (the beginning of the Retrosheet era) to determine which catchers have been the best at preventing wild pitches and passed balls. Since both rates have a lot to do with the pitchers (particularly if the pitcher is a knuckleballer), you can't tell a huge amount about a catcher from his raw PB and WP numbers. What Forman did was to determine an expected number of PB and WP for each catcher, based on the wildness of the pitchers he caught (which he estimated from a pitcher's K, BB and HBP rates).

For example, Forman estimated that Doug Mirabelli saved 7 WP/PB last season - he allowed 13 WP or PB, but an average catcher would have allowed 20 given the same pitchers (particularly, Tim Wakefield).

One surprising conclusion was that the catcher that Forman determined to have saved the most PB and WP was Mike Piazza. I had always thought Piazza's defense was better than you'd expect by his inability to throw out baserunners, but that still surprised me. Ivan Rodriguez, on the other hand, turns out quite poorly here. The difference (about 55 runs over their careers) is enough to make a sizable dent in Pudge's lead over Piazza when it comes to throwing out baserunners (about 200 runs). The numbers don't appear to be affected by catching the same pitchers year after year - Piazza's numbers were excellent with the Dodgers, and they stayed pretty much the same with the Mets.

Some particularly interesting slides if you don't want to read the whole thing:

Single season best
Single season worst (no shock to see Bob Uecker here)
Career best
Career worst
Active best
Active worst

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