How does a defensive back/player DC become a head coach and revolutionize NFL offenses? Won so much and changed NFL offenses so much he was put into HOF one year after he was fired after 29 seasons, 20 straight winning seasons, and 2 Lombardis?
I'm not saying Dennison is going to be the next Tom Landry, but this idea that a guy can only play/coach 1 position is silly IMHO.
If you know football, you know football.