Gruden sensed a disaster this year, so he is bailing out now, and giving himself a decent chance when they head to Las Vegas. Gutless move, though, as he is basically trying to buy some time. Oakland has a chance to go 4 and 12 this year. I'd still like to see Gruden do well, but now he can't win, because if they are decent, then people will blame Gruden for not keeping Mack, and if they are terrible, he will get even more blame. There is almost no chance to win at this point, unless they win the Super Bowl. Anything less, and Mack will be seen as the difference between good and great.
My guess is Oakland goes 3 and 13.