Play callers are the juice. Take for instance the 2016 falcons. They had Kyle Shanahan calling plays. He left and the falcons let their whole offensive coaching staff go except for Raheem Morris who isn’t even an offensive coach. They had scored the second most points through the playoffs up until that point at somewhere around 33PPG and Matt Ryan won MVP. The next year they brought in Sarkasian and were lucky to score 20 per game.

ESPN once had a two INT Charlie Batch game as its best game under QBR. Then they went back and fixed their model.

Peter Principle. Coaching and playing are two different things. Sure, they overlap, but just because you played doesn’t mean you can coach.