I know it's happened before, but strange that he would leave before playing in a BCS bowl game because at NC State he will never get close to making it to one.
Strike while the iron is hot. If NIU were to play in a BCS game (not guaranteed) and get blown out, his stock might have diminished. Plus, NCSt isn't going to wait a month to fill the position, with the recruiting deadline in early Feb, and God knows what might be available in Jan.