Well said shore dad. Pretty much the same uestions ee all have. Player mistakes as your standard excuse for poor D falls squarely on staff this far into season. Quick athletic LBs are perfect for a 3-4 if and only if DL,particularly NG, can keep OL off them. If you watch tape of FU or most other games you can easily see that LBs are usually engaged with blockers.
CBs are not that bad but hard to cover if QB rarely pressured. D issues start with DL and cascade back. Are they bad players ? Nope. Not particularly a good fit for 3-4. Problem is coaching.