I read a lot and don't post if ever, but I had to jump in on this thread.
I agree with this to an extent and I'll even take it a step further. The issue with the Bills is that they use their full arsenal of plays and situational tendencies (and answers) a lot throughout the season. What I mean by that is that by the time they play in very meaningful games, everything they do is on film and everything they like to do when it matters the most is known by the Chiefs, Bengals, etc. For example, the 4th and 5 play and the corner blitz, Spags knew the Bills were going to condense the formation, use either a 4x1 or 3x1 set and run a variation of the mesh concept, so he sends 6, heavy from the 1 side because that would be the hot generally in a zone look - because Spags knows the Bills aren't going to run a quick out or hook up Samuel.
Same thing for the 3rd and 9 play that sealed the game. Bills are desperate, need to get pressure to get the ball out of Mahomes's hand quick. So they dial up man cover 1 as they have a bunch this season, and Andy Reid runs a great slice concept for the back out of the backfield.
Long story short, when we've had big games the reason we are in them is because of Josh Allen's abilities to win individual plays with his arm, legs, and even mind now. But we don't have a stud chess piece on the other side of the ball that can go win a play or win the game with one play. We thought we were getting that with Von, and that hasn't happened. Garrett gives us a chance to have that chess piece so that no matter what you call - we have a guy that can win the play/game.
So until we can be better at situational football (when it matters most), we need better chess pieces.
(Disclaimer: I think we have one of the top 5 head coaches in the game today - not a knock on the job McD does and continues to do. Just keep some things in the bag, or at least have different answers to the same question.)