It's like how many licks does it take to get to the center of a tootsie role, the world may never know.
Seriously, what coach has won big without a top quarterback? Bill Bellichick is widely considered the best coach of his time. In seven, now eight seasons, without Tom Brady his record is below .500 with, I believe, one playoff appearance. Mike Shanahan won a super bowl with John Elway, but his teams dropped significantly without him. Don Shula made it to the super bowl with four different quarterbacks, which was pretty unique. One of those was David Woodley. Quite an accomplishment.
I guess the answer is you need both.