McVay has coached 4 starting QBs.
RGIII who with his Dad was on the way out. And he coached up a nobody in Cousins who is on record that McVay was instrumental in him being a starter.
Goff, who was routinely shit on when McVay came in. Who he coached to a Super Bowl prior to Goff's confidence eroding.
And Stafford, who was questioned in the media re: whether he was good enough to win a playoff game. He did in fact win that playoff game, and put together one of the most impressive postseason runs by a QB in history, with zero run game to back him up.
So. To criticize McVay the best approach is to start with the fact that his inability to consistently balance his offense puts inordinate pressure on passers. He gets the most from them, but I suspect wears them down mentally. Of course Stafford suffered so long under poor coaches that he probably still appreciates the offense and calls in spite of all that.