You guys have it mostly right. There was an attempt by Powers and some to effectively say a public goodbye at the banquet but Mack went petulant. Completely balked at the terms he'd agreed to.
Patterson was hired to make changes. There was never going to be any other outcome absent a run to a BCS game and maybe not even then.
Powers is getting something of a bad rap. Mack f*ed Powers over. Why we're going to continue to pay the guy is a f*ing mystery to me. With his actions of late, good riddance and come back in about ten years when I've calmed down.