Butch played Peterman because Worley wasn't tucking the ball on the read option and he thought a few qb runs with a safe passing game might win the game, as UF and other teams didn't have to defend the qb run. He also kept noticing how blatantly timid and scared Worley was looking and he was never running. Actually, after the benching, he made more plays with his legs.
Peterman hadn't shown any indication in practice that he would too go into a deer in headlights mode and the turnovers basically sent him and everyone into shock.
**** happens. He was trying to win and at the time, Worley hadn't shown that he could beat anyone. However you look at it, Worley came back playing better, for whatever reason, and beat a top 10 team in the process, while using his feet on a couple of big 3rd downs.