There was no proof. Also, in response to one of your prior posts, he was not convicted of rigging games.
There was proof. No, the Ref. in question didn't rig games. What he did was collude with gamblers to determine who was most likely to win games due to knowing who was going to be refereeing certain match ups. In truth, he should not have been the one to be convicted. The referees in question should have been. He's just the guy who got caught with the underworld guys.
The fact that this guy could successfully predict games, but wasn't fixing them, is strong evidence of widespread malfeasance in the NBA refereeing ranks. He also stated that the League was encouraging such behavior. Did the League say, "You got us"? Nope. I've never seen a head of a non-profit, business CEO, politician or judge who didn't deny, deny, deny when they were fingered. I'm not saying that being fingered and denying automatically makes one guilty. However, denying doesn't make one not guilty either. In this case we have enough evidence to make a wise individual think twice about gambling in the NBA.