So how often do pitchouts succeed?
In looking at 2003 and 2004 data I found the following:
Stolen bases: 100 (43%)
Caught Stealing: 124 (53%)
Passed Ball: 2 (>1%)
Wild pitch: 5 (2%)
Pickoff: 1 (>1%)
It surprised me a bit that the stolen base percentage was as high as 43% when a pitch out occurred. When you add the other positive outcomes the percentage raises to 46%. That's not bad considering that the defense guessed right in these 232 instances.