I dunno about being too old to coach. I just think that maybe the events of this season were too much for him to deal with. How many coaches could deal with the violent death of a marquee player in the middle of a season, and lead his team to 4 straight wins and a playoff appearance.
I know that players have died before, ie. Korey Stringer and Darrent Williams, but not in the midst of a season.
Thats alot to deal with, plus his lost his starting QB to a devastating injury. Too bad for the Redskins fans, though...little Danny will probably make another bonehead decision on the next head coach..