I don't remember if it was last year or the year before but when I would do these AMAs I'd always get questions about the defense's tackling--why it was bad, if they needed to live tackle in practice, etc.
At the time what I said was it's this cascade effect (someone can search for it to get my exact words)--basically you have guys pressing, trying to do more than their job, to make a play b/c they don't have confidence in their teammates or the scheme or whatever it is, so THEY need to make a play. So now they're getting out of their lane, trying to force big plays instead of letting the plays come to them. That's when you get bad technique and discipline, which leads to missed tackles, blown coverages, penalties, etc.
How many actual new faces are there on the defense? Where is the massive upgrade? Will Harris???? Chase Young??? Lattimore didn't even play this game.
No. It's the same guys, playing more sound, more composed, and trusting each other. Just like the offense--it's almost the exact same players, playing with confidence.