Well since you don't understand basketball, I'll be happy to tell you.
Alabama's Grant Nelson was abusing every player we tried to guard him with. Withers was the only player who was having any success guarding him. So he was on the floor for defense and it was in fact working.
The problem is, Withers is a moron. He wasn't content with just playing his defensive role. So he took a shot he shouldn't have.
See, if you actually understood anything about basketball, you would never have had to ask that question. It all happened right in front of your eyes, but your potato brain couldn't understand it.