The issue with McDaniels is that he doesn't seem very adaptable. He can game-plan well, prepare, find a scheme that suits his personnel, but when forced to tweak things during a game he either, a.) is completely unable to, or b.) overcorrects.
Just really lacking in tact/nuance, seems overly reliant on game-planning, doesn't seem capable of making small tweaks, and telegraphs plays based on personnel/formation. Finds something that works well and sticks with it until it doesn't. Everything just feels rigid and heavy-handed.
I mean, the fact it took them 55 minutes to change the offensive approach against LAR in the 2018/19 Super Bowl is a really good example of that.
The best analogy I have is : the kid who could ace tests when presented with the word-for-word questions in advance, but if you take those questions and tweak them slightly (maintaining the same core concepts but changing the wording) they crumble.
He's a darn good OC but he's not without his flaws.