I'm not trying to be that guy, but can you please fix the spelling in the title? It's staring at me.
To answer the topic, it's both of them. Belicheck does a great job of putting players in a position to win. He keeps signing guys who were considers busts, reducing expectations on the field, and getting their original potential out of them.
Take the Bills, eliminate the mistakes, add Tom Brady 🤢, and slowly eliminate the losing mantra. I think you have the same franchise.
Good coaches get you to the playoffs. Great qbs, get you to the championship game, great coaches win you the super bowl.
It's everything together