At GCSS he severely clanged every track he mixed, some of them wern't even beatmatched, and he ragged the console around while brocking out on the top of the stage. I think he was doing something that he would have prolly usually done during a peaktime set in Iowa, but he was the first dj to play (at 4.00pm in the afternoon), everyone was sober and paying attention, and being on the Valve seemed to make it worse. He literaly got booed off when he finished, and afterwards if another dj did a bit of a clang or made a little mistake, the mc would say 'oi, you're having a bit of a Starscream moment there mate' as a stab at what had got on earlier. I just sat there and watched him fuck up from the doorway at the back of the tent.
As for Slipknot, yeah he was djing for a long time before that, but Slipknot is what he does best, I mean that's what he's famous for. If he was better at djing dnb we'd have all heard of him before Slipknot, but that's not true at all. Everyone knows him as that dj guy from Slipknot, and that's gonna follow him for a long time. And he is a background dj for them, he does little scratches and samples, and jumps around going crazy, but that is not THE main part of the band is it?
That's just my opinion, don't take it as divine law or something.