As some you may have seen (here and here) there is video from last nights ALCS game of what looks like Mariano Rivera spitting on a ball. I am not going to judge what he was trying to do, instead I will look at the physical aspects of the "spitball" and compare it to the other pitches he threw last night. The main advantage of spitting on a ball is to change the spin and direction of the ball. If there was spit on the ball last night, the ball would act significantly different than other pitches Mariano threw. I went to the ever reliable BrooksBaseball.net and saw that the spitball pitch was labeled as a cutter. Imagine that, Mariano Rivera throwing a cutter. There were nine other pitches last night labeled as cutters. Here is the spin and break information on those nine pitches:
The suspect pitch was not unusual from the cutters he threw. Even if he was trying to spit on the ball for effect, he got no change in break or spin. People can continue to argue his intent, but for actual effects of the "Spitball" there was no actual advantage gained.
The actual mental aspect gained might be huge as players will be looking for him spitting now. It is not like they need something else to worry about when facing Rivera.