You'll see that under McVay the front office immediately added a LT and settled down the OL, as well as added wideouts who can play in this offense.
Compare that to Fisher undoubtedly pushing the Rams front office to sign Tavon Austin, or Mark Barron, or Alec Ogletree. Basically under Fish players who were "his guys" were rewarded with contracts. Under McVay guys who fit the scheme and play well were rewarded.
It's an enormous difference. And it demonstrates how far ahead young Coach McVay is of a seasoned veteran Coach Fisher.