For me it is all related. Butler needs to learn how to coach better or come up with a different scheme.
For years we were all told that only a vanishingly small minority of players can handle the demands of being an NFL QB and there has never been and will never be enough of them to go around. Everyone accepted that. Over the last 2-5 years we have seen an increasing number of offensive coaches refuse to accept that as an answer. They have changed what NFL offenses do at a fundamental level. This has shifted the demands on the QB position and expanded the pool of acceptable QBs.
There has been a similar overhaul with offensive lineman, as colleges were simply not producing the traditional types.
Butler and most NFL defensive coordinators are doing the same old stuff. And they are mostly helpless bystanders as NFL offenses spread them out horizontally and vertically at the same time and hammer away at any weakness until something breaks. The only answer anyone has is "pass rush". That is a component of an answer but far from a total answer.
The same types of innovative and adaptive thinking that allow an increasing number of players to flourish at the QB position needs to be brought to bear on the defensive side of the ball. And I simply do not see it from Butler. The only way his defense succeeds is to get enough pressure to throw the offense off balance or to have a better collection of athletes on his side of the ball. But schematically there seems to be very little being done to help those things happen.