Bill Belichick teams often have less talent than the other team (when it comes to the playoffs).BB is in rare air, but just have a look at how good their list management strategy has been
Kansas City this past season had a better team on pure on-field talent, but BB out-coached Andy Reid (again).
BB is big on smart players, teaching situational awareness and being relatively good in all three phases (offence, defence and special teams).
Coaching matters (a lot).
But I agree list management is equally important.
David Teague has shown me much, he adapts within game something I bemoaned about Bolts. Our game-day coaching means we are no longer a predictable / easy team to play.