I think you've cut to the heart of the matter here.
McDermott was on the record saying "what he's doing on offense is almost revolutionary". He then proceeded to dissect and neutralize what McDaniel was doing.
Other teams paid attention and adapted the principles if not the method. And McDaniel hasn't counterd as yet.
It's rather the same thing as Daboll. In 2020, when Josh took a giant step up as a passer, we were shredding teams. In 2021, when Daboll committed to doing what he did in 2021 only more so, the Pittsburgh Steelers totally neutralized us in the season opener and other teams took note. Not immediately, and not all teams could pull it off, but the blueprint was out there and we had some critical losses. We don't know if Daboll would have adjusted in Buffalo 'cuz he left for the Giants, but Dorsey, who kind of took over as "Daboll lite", got solved (and replaced).
But it's not because McDaniel is a nerdulent-looking capris wearing pustule that he'll have problems, if he's having problems. It will be because he's been "solved" schematically and hasn't adapted.