What's interesting is that Pepper Johnson was never brought up as DC for the Patriots. I find it interesting because a few weeks ago, it was either Irvin or Deion who said that the best coordinators and head coaches are guys who either excel in the safety, wide receiver, QB, or corner back positions. Why? Because they have the whole field to see and analyze and read. So that talent naturally translates into being a coordinator, where you can see everything the opposing team does.
Of course, there are the exceptions such as students of the game and such, but I always found that interesting.