Several good responses, it is a combination of all, Improper Lean Angle, Improper braking point, Improper Throttle response, Improper entrance. All lead to him dragging the floorboard mounting arm removing weight from the rear tire.
I ride my SG very hard and put away my fair share of crotch rockets. The bike has limits besides speed and you have to learn them and lean angle is a big one. Get off the bike, stand it up and turn it in! It will go. Feel hard parts, don't do it again lol. It actually handles very well and has great torque out of the turns!