Agreed, and for the short term that worked. Manny's scheme worked originally as well. But can it hold up after coaches have a year or two of film to scheme around? Manny's obviously didn't. We don't know about Robinson's defense because he was let go with Mack.
PK went for years fielding a pretty salty defense with Washington. I don't think he forgot how to coach and unlike Manny Diaz, he actually had an extended history of success prior to being hired meaning offensive coordinators knew his scheme. Is he maybe too stubborn in sticking to his scheme instead of adjusting to his personnel...maybe that's the case, maybe it isn't. But that also depends on whether you take a short term fix view or a long term view and whether you think the problems are all coaching or at least in part on the players.
If he wants his scheme to be effective, the players have to live it and practice it and learn how to execute it under live fire. That takes time (more than a few months of practice and 9 games). Unfortunately a lot of our fanbase is like asking a 7 year old if they want a ice cream now or a bicycle in a week. They'll take the ice cream. Do what's best right now, right now, right now. Not tomorrow, right fucking now. You never get the bike if you can't have the least bit of patience.
You don't build a culture like that, you don't build build consistency like that, you don't develop player leadership like that. So I'll give PK the benefit of the doubt for now, no matter how frustrating it is (and I was screaming how much he sucks in this last game). If we aren't seeing the benefits of learning the same system towards the end of next season, then maybe its a different discussion we're having.