Which is entirely plausible. Put yourself in his shoes... any coach wants to take the next step and coach big time football. Mullen is hungry enough to do that (he'd be stupid not to). He can stay here, live with 6 win seasons and never really be in serious contention for a big time job without having to go somewhere else... or he can go somewhere (even if it's "lateral") where he can get some wins and buy time to take the next step. The question is, does Mullen feel he has peaked here or not?
The reality is, I would be shocked if we win more than 6 or 7 games next year... which wouldn't hurt Mullen here... but it will hurt his stock even worse, and it would take several 8+ win seasons to get it back. Mullen ain't stupid... and I can assure you he has thought about this.