I guess I'm not picky about what's wrong with the defense considering they've been more stout against KU, KSU, and UT* than any of the other teams they've faced and will likely face. It seems like a pretty big ask to keep KU below 11 points, KSU below 7 points, and UT below 21 points. I don't disagree with anything you've said but I think even Bill Parcells would agree that a finger should be pointing at special teams and the offense (and not the defense) for this particular football team...
I don't necessarily disagree with what you are saying just that both things can be and are likely true. Getting enough pressure on 3rd and longs in big games and getting enough pressure to cause turnovers have been continual problems, regardless of the overall numbers. I think this becomes magnified when we have an offense that can't be relied on to score points and/or punch it in when in the red zone.
In general our coverage has been good (when someone like Tampa doesn't blow an assignment) but the pressure has been abysmal. It's inconsistent and not really conducive to forcing turnovers, something we really need. With Rose, we had an LB who could be relied upon to shoot the gaps, not miss tackles, and make plays in coverage. We simply do not have a LB that can do that (nor can the group as a whole) and we need to adapt.
I would gladly give up more yards if it meant more turnovers and more drive crushing sacks/pressures. I think the defense has the ability to do that, but NOT when we keep conservatively rushing 3 guys with a weak LB core. The defense is good but I think it can be more impactful and game changing. With this team, if we want to win, that's what we'll need.