the umpires made the right call but the call is strange to begin with... it's sort of like major league baseball's version of the tuck rule. it actually doesn't say anywhere in the rule book that he can't slap the ball away... it says in the umpire's addendum, a section added to the rule book to "clarify" certain rules, that you can't slap it away whatever... they made the right call. it's confusing because if a-rod would have just barrelled arroyo over, dropping the shoulder right into his glove in an effort to dislodge the ball, there would be no interference because a-rod has the right to the basepath. but when he makes that slapping motion, it's illegal. confusing yes, right call, also yes.