I can't think of the last legendary coach that went to another team and won anything of note.
Parcells came very close after rebuilding the Jets from 1-15 into a 11-5 and 12-4 team that went to the AFC title game twice.
Holmgren came close in Seattle after leaving Green Bay but was younger than some of these others.
Gibbs didn't win the second time around. Jimmy Johnson didn't win. Ditka didn't win.
I don't see Belichick with full control doing a better job of drafting in a burgundy and gold sweater rather than a blue and silver one.
And THAT is the at the crux of the recent failure in New England.
The Patriots ability to draft the Willie McGinnests, Ty Laws, Vince Wilforks, Logan Mankins, Rob Gronkowskis, etc. is GONE.
Their recent draft pick history is little better if better at all than Ron Rivera's.
And Belichick is not going anywhere just to coach players someone else gives him.
Any GM hire will be a guy that is taking orders from Bill just as Mayhew is taking orders from Ronnie Ron