Grogan was on a virtually identical career track to Brady - until the Super Bowl was stolen from him. The Space-time continuum is fluid; we can project how it could have gone otherwise but we don't have proof. Would Sullivan have behaved the same in the Hannah-Gray holdout, I say yes. The second major barrier to Grogan winning again is Stingley, who is as important to that era as Troy Brown is later. That second atrocity was committed at the very same venue against the very same team and coach. There simply is no other opponent who could ever be loathed as much in our history, forever. The consequences were devastating. Conversely, as we saw this century the credibility and pomp associated with being a Super Bowl champion, more than anything else, gives a team an annual objective and standard to pursue that is a known accomplishment. We've been there, and we want to go back.
Grogan responded to adversity primarily with personal character, and determination. He is very, very much like Tom Brady. He is likewise ultra competitive and highly emotional. He did not have the obvious talent of Plunkett, but he had exceptional mental aptitude for the position and off the charts leadership qualities.
Even through all the injuries and front office/management turmoil, Grogan put the Patriots in contention for the Super Bowl title from 1985-87, and then the third member of the Pats' Holy Trinity of modern quarterbacks took the reins in 1988, local boy Doug Flutie.
The parallels between Flutie and Brady are also striking. In his first extended NFL starting opportunity, Doug like Tom took a losing collection of talented players with significant playoff and Super Bowl experience and put them on the doorstep of glory. That coach chose the suicidal route of putting the vastly inferior number 11 losing Super Bowl starter back in with the same results we would have seen if Belichick did that in '01, and Brady would have likewise had to go win somewhere else.
So given all the details, I very easily see Grogan winning at least two or three Super Bowls under Fairbanks. I don't think Chuck leaves if Darryl isn't paralyzed.