I someone disagree on your assessment of the improvement of the LBs. I think the biggest reason for the D’s improvement has been the Dline play, freeing up the LBs to roam and make plays. For sure Gardner has stepped up his game and that has been a big reason also, but the DL has not only commanded double teams but gotten pressure.
The most obvious reason for the DL improvement has been the ability to play Young at DE. He is a lot to handle for opponents anyway but paired with a DT in the middle he has been even better. And then we have Hamilton, who transformed his body in the off season and is all over the place pressuring the QB.
This pressure from the DL and LBs has made our DBs better and directly led to a least two INTs against Ark, including the flea flicker.