What's your source?
Some little MMA website did a video interview with Brett a while back and they asked him why he no longer trains at Minnesota MMA. He told them in a nutshell, He was one of Brocks main sparring partners while he was helping Brock prepare for Heath Herring and the whole time Brock was throwing as hard as he could, even when they were on the gound with the 4oz'ers. So he said he decided to do the same and ended up flash dropping Brock twice and finally knocking him out cold, which resulted in him getting the boot. I don't feel like looking for the vid right now but I saw it on the UG, i'm sure it's there somewhere.