Its not whether he is making the proper calls or not, in my opinion, it's the fact that he almost always shows some sort of bias in the games he officiates in. I have been watching this league for nearly 20 years now, I can't count how many I think he actually had a significant role in the outcome. I am not saying he is on the take or anything, I just think his high attitude on himself has been hurting his ability to call games effectively.
And again why do you think he continues to keep reffing in these BIG GAMES? That's my point. No other reason then to think this way. Why would an NBA office want a hot head official with a quick whistle reffing the BIGGEST GAMES on stage? Doesn't make sense. The NBA wants it this way, and it's not by accident. If they didn't want him out there, they would have him officiating period. Enough said