It shouldn't matter the protection when you have the skill guys the Rams have. Any QB should be able to make that work with the guys the Rams have. Yes, I trust McVay. He's the guy that took the Rams from the worst offense under Fisher, to the best in his first season. But, that was with a great o line and a QB that can only function with great protection. Rams no longer have that. They never will given the cap again.
If your QB can't scramble, and he can't read a defense in 3 seconds, you're screwed. No offensive coordinator can make that work. If you call the long developing play, the line doesn't hold up long enough. If you count on your qb making the right quick read in 3 seconds, and he can't do it, your passing attack is done for.
This is a Goff issue. It's not McVay. McVay's calling the plays he thinks Goff can execute best.