I think this is simple - McVay built this fined tuned offensive machine built around motion and deception. For 30+ games, it had the whole league confused. Then, Matt Patricia exposed it, big time ...
The defense doesn't need to panic, doesn't need to shift - just hold your position, play 2-deep safety or 4 quarters, and eliminate the big play ....
McVay has shown NO ability to adjust at all .... and Goff looks like he did under Fisher ...