Anibal Sanchez of the Florida Marlins threw the fourth low-hit game of his career on Saturday. Sanchez raises an interesting question based on how PITCHf/x classifies his throws. If a pitcher can fool a computer, does he also fool batters?
The following graph shows the spin of Anibal's pitches in the 2011 season:
The big orange spots represent his fastballs. The green spots below are the slider and change up, the slider moving toward left-handed batters, the change up toward right-handed batters. The blue blob at the lowest point on the chart represents his curve ball.
PITCHf/x has trouble with the slider, however:
Does Sanchez throw a hard and a soft slider? Probably not:
There is a fastball that the computer model doesn't identify well. It mostly looks like a cutter, but supposedly, Sanchez does not throw a cut fastball:
Sanchez throws five pitches:
A four-seam fastball that has a good deal of cutting action but doesn't sink like many other cutters.
Compare that to his four-seam and two-seam fastball, the latter called a sinker by PITCHf/x:
Notice that there is some overlap between the fastball and what is called the cutter.
So are batters fooled? They are a combined 61 for 254 on the slider-cutter combination, a .240 BA. They hit .252 overall against Sanchez, so that combination does seem to fool them a bit. Batters slug .378 on the pitches, versus .402 overall, so they drive these pitches less as well. Finally, they strike out 29% of the time on the slider-cutter, 24.2% of the time overall. The pitches that are fooling the machines are fooling the humans as well.