McVay is a terrific HC and Offensive mind. I think time is likely to reveal that McVay made the most of Goff, and Goff is unlikely to ever again achieve that level.

Adding a ready to go, top tier QB that can figure things out on the fly... like Brady, Wilson, and Rogers... simply changes the balance of the equation. QBs that good can not only make the most of what you have, they can help you figure out how to game plan and how to specifically run plays.

McVay was a genius his first couple of years. Then he fell back to really smart. Now he's a genius again.