I've always been very skeptical about Gruden. He won in Oakland, but the Raiders had a lot of talent back in those days. Gruden managed to keep Al Davis away long enough to put in a real offense, and that talent won until he had a falling-out with Davis. Bill Callahan came in and screwed it up within two years.
Then he won a Super Bowl, over dopey Callahan and Davis. That was the last good thing he ever did.
Over his last six years in Tampa, he was 45-53, and had two horrendous losing seasons.
I've always said that we fired a coach who won a championship and then went on to win two-thirds of his games for a decade after, and who had two losing seasons where he was just under .500.
I don't see the attraction to Gruden, other than he has experience in the "almighty" NFL (so did Al Groh and Callahan, not to mention a certain Lane Kiffin) and a wife who was a cheerleader at UT sometime back in the Reagan administration.