Ed Werder with GaC on ESPN 103-Dallas...

RECAP by TrickBlue from a sports forum:

He said "Physically I could still do it, mentally I have just had enough. It's time to let go". He is going to assist Jerry and Stephen and will remain at VR for the time being.

EDIT: Recap added

Werder:
I talked to Bill briefly on the phone today. He told me he agonized about the decision. He realized the finality and that this would be the end of his career.

I think it wasn't a money deal. There was no buyout or exit bonus. He's walking out on 5.5 mil. I don't think it's a point of contention. I was told it was very amicable and no hard feelings. He thinks this team is close and that it is a better franchise now than the record indicates.

I think Jerry has a pretty good idea of what he wants to do. He's had two weeks to have a plan B ready and I'm sure he has something in mind. He wouldn't risk his franchise by not being prepared.

Many have said this relationship would end on a bad note and that hasn't been the case. I was told Jerry was both disappointed and shocked by his decision.
He's so convinced he doesn't want to coach that he walked away from a lot of money.

I think/hear his list contains Norv Turner to help develop his young Pro Bowl QB Romo. I realize some will think that Dallas would be attempting to go back 10 years ago. He's helped Brees, Smith the Dolphin QB's. Everywhere he's been he's developed a great running game and good young QB's. Norv is not a puppet. He wouldn't put himself in a bad organization. You have to look past the Raiders, Al Davis is impossible. Also look at Snyder, no one has been really successful under him. Wade Phillips is another name. Jerry likes him personally and he has been exceptional working with the 3-4 defense and getting pressure players.