I'm listening to his Press Conference from today... Parcells has been outstanding in terms of offering advice, or if he has a question being able to call Bill. Along with guys such as Weis, Romeo, Kirk(Ferentz), other Assistant Coaches. Lovie Smith called him the other day to wish him luck, and other coaches have done the same thing.
It's always good to take advice from others in a competitive sport. I've done a lot of competitive things, and I've learned probably the most from inferior competitors. The inferior players generally have good theory, or you can see why something doesn't work, it's just they fail in the execution phase or fail in knowing what to apply and when quickly enough. They think things through moreso because they don't win as much, for whatever reason. The trick is to take what they have to say, and then use it better than they do. I'm sure that's what Mangini can and will do, he won't just ignore it.