So I am just going to put this out here, if it ticks some folks off so be it but it needs to be said. I am not sure everyone fully understands the DC job strategically. The "it needs to be innovative " junk is kind of well junk.
As a DC I am playing chess with the guy across the field calling the offensive plays, even IF you are an aggressive defense it's still from a reactive position per se. The real work is leading up to each game, looking at tendencies, what they do by formation, etc. If they use motion to check coverage we would install a silent switch so that the QB wouldn't have an easy get-on man or zone looks.... your fronts need to match coverage...I could go on and on.
Here's the point, the best DC are generally not the "new " guys with new ideas( that cracks me up) or the old tried and true ones either. The very best staff and coordinators work hard week after week on the details going into a game, their preparation is exceptional and their work ethic is off the charts. If you add that with solid leadership qualities you'll generally find a great coach.