One of the interesting things during the coach hiring season in the NFL is fans praying their team hires an offensive minded head coach. The rules of the league certainly benefit the passing game, and the teams that can exploit that have an inherent advantage. A basic look at the head coaches remaining in the NFL Playoffs shows that one need not be a hire from the offensive side of the ball to build a contender.
Five of the eight coaches who got their teams to this point are defensive guys. Does this prove defense is superior to offense? Of course not. It just shows good head coaches have different attributes and bring different skills to the table.
Many of the defensive coaches do have dynamic offenses. Since it isn't their specialty, however, they find smart offensive minds to whom they can delegate or in the case of Belichick learn more and more about offense as the years go forward. Make no mistake. The defensive head coaches are still responsible for the end results of their offense. They just don't need to necessarily be hands on with the unit to find success.