"... in his own eyes, his own hires are not worthy of being coordinators." It's a given that in McVay's eyes the guys he hired were not worthy of being coordinators. To me that's not the same thing as saying they shouldn't have been hired for the jobs they were hired for.
"Internal promotion is a good policy because it fosters continuity." I'm a big fan of internal promotions, and would always promote from within when I could, even if there was an external candidate who was considered slightly better in a vacuum. The idea of maintaining continuity, the morale of the team when a coworker was promoted over bringing someone new in, etc, all make internal promotions ideal. But there were times when an external candidate was head and shoulders better than my internal candidate(s) I would hire them instead.
The Rams are addressing the continuity issue by having Morris run the same (or at least very similar) defense that Staley ran. I am hopeful that works out, as I am sure you are as well.
But continuity isn't necessarily the be-all end-all. Staley succeeded Wade, ran a different defense, and that worked out OK.
AlbaNY_Ram