Yankees fans, prepare to be unhappy. The video you are about to watch has the potential to be very damning for Mariano Rivera and the Yankees. This is footage taken during the bottom of the 10th of Mariano Rivera – on the mound – apparently spitting on the ball. If this is true, it’s very bad news for Rivera. Spitballs have been illegal since the freakin’ 1920s, as they are “highly dangerous” for batters.