I might be a bad teacher

My boys love to play basketball, but they don't really know the rules.  They're getting a lot better about not pushing each other, but when the ball is up for grabs, they're not as nice.  One of my boys, let's call him Alex, is a bit of a snot.  If I say up, he'll say down, and he's not a huge fan of sharing.  This morning two of the boys are chasing down the ball and one of them (um...how about Bernie) clearly has the ball in his arms.  Alex reaches both arms around Bernie to take the ball away and Bernie's natural reaction is to shield himself and shoo Alex away.  So when he accidentally pokes Alex in the eye I don't really do much because I figure the kid had it coming to him anyway.  That might be why I'm a bad teacher.