They were 18th in offense that year. Truly impressive. His offense in Miami was 17th, 28th and 26th. The Jets were 31st and 32nd. So outside of 1 year with Peyton Manning running the offense he never even cracked the top half of the league as an OC (yes, he was the OC in Miami despite naming his yes man to the position).
How does that make one qualified to be a HC? So we should go find an OC who's never had a top 15 offense and been in the bottom 3rd for most of his career at the thing he's supposed to be a genius at?
Gase was never qualified. Sometimes, when you find yourself in a hole.. stop digging.