I think he's one of "the four constants" in the New England dynasty...
Belichick and Brady, of course, plus Scarnecchia and the mysterious Ernie Adams.
For 20 years now the Patriots' OL has largely kept Brady's uniform clean. "Largely," I say, because of course that's hard to quantify and Brady's skill set has almost always made his OL look good... He doesn't hold onto the ball any longer than is necessary and in turn that's exactly what his OL gives him depending on the route/hot read.
The O-linemen come and go from Foxborough, almost never a high-rounder, rather a "next man up" program under Scarnecchia... he simply coaches them up.
I don't know if the Patriots under Scarnecchia have ever had a rush of injuries such as the Rams this season, but I wonder what kind of chicken salad DS would have created if he worked for Kroenke this year rather than Kraft.
How many DCs have left the Patriots with no drop-off in SB-caliber playmaking? Vrabel, Patricia, Crennel, etc. Of course that's because Hoodie is really the schemer and he now is grooming his son from what I've read.
But I've often thought Scarnecchia is the one staffer Kraft, on Belichick's insistence, would give a blank-check contract to stay on. As I recall Scarnecchia retired once but that was short-lived, maybe one season.