Speed Kills

Tom Tango posted an interesting question at The Book Blog, asking people to estimate the wOBA of batters against a series of pitching machines that threw fastballs in the strike zone.  In his senario, there were a number of machines, each threw at a different speed, but each threw with the same spin and with the same release point.  The machines threw in the strike zone, but the location within the strike zone was random.  The batter knew the speed and the spin, but not the ultimate location of the pitch.

PITCHf/x data does not allow us to answer this question exactly, but it does allow us to get an estimate of what the distribution might look like.  The following table shows results for fastballs in the strike zone from 2008-2011 form pitchers with at least 200 PA against their fastballs.

Speed Range	Number of Pitchers	Average wOBA
< 85	4	0.361
85 to 89.9	63	0.344
90 to 94.9	197	0.335
>= 95	21	0.315

The wOBA reported here is the average of the individual pitchers, not the actual wOBA.  It does the effectiveness of fast fastballs versus slow fastballs.