Here is an interesting thought, I think. More and more teams have gone to young offensive coordinators whose ideas are congruent with the current game. My sense is - and I could be shown to be mistaken - that teams have been less proactive in hiring younger defensive coordinators.
This seems a bit odd. Maybe the older DCs, set in their ways, are married to ideas and schemes that worked once and have become outmoded. Mike Nolan has, for many years, been a competent DC in the NFL. He might never have been the best, but he was competent. Suddenly his scheme seems to have more leaks than the Titanic. Has he forgotten how to coach defense, or is the opposite -- he remembers too much that is no longer effective?
I don't think Williams is the answer. I'm not sure Wade Phillips is the answer. I wonder if the answer is to turn to someone whose background is more tuned to defending modern offenses.