We should be a bit better on the interior DL with returning guys. We should also be better at S with both returning guys and new kids and a new DB coach. If we get better LB play also, and our D could so noticeable improvement. Fixing the middle should help manage the horizontal plays. No guarantee and need DEs and LBs to step up, but I'd guess we'll see some improvement this year and folks will want to crown Manny for it when it's probably more going to be about having fewer weaknesses and a stronger base.
DL
Interior DL should be somewhat better, but we don't have the talent there such as we're losing at DE. So compared to this year's DL, it's a net decline to me.
Simpson is a wild card, but is he much of an improvement over Stroud? I like Simpson, but Stroud was also highly regarded.
The real question with the DL is whether our "everybody pin your ears back and get 7 yds deep into the backfield asap" style play will continue, or will more gap integrity emerge? As has been amply noted, the lack of gap integrity was a huge problem in 2020. That's not the DL coach's call, it's part of Manny's/Baker's scheme.
LB
You caveated with "if we get better LB play" and also noted "no guarantee". I'm not optimistic we'll get better play. I don't see much reason why we should. Same guy is coaching them in the same defensive scheme. And from a personnel perspective we didn't end the season with any LB looking like they're on verge of taking the next step.
From the last two games of 2020 to the first games of 2021 i see no reason to expect any of Jennings, Steed or McCloud (if he even plays the position anymore) to play any better. Similarly, nothing about Flagg, TAC and Huff says to me that they're all of sudden going to start playing much better in Sept/Oct 2021 than they played the last several games in 2020.
My conclusion is I don't see much reason for meaningful improvement out of this group. Additionally, since I expect our DL play to be worse than 2020 it will put even more pressure on this already weak position group.
DB
You and I both expect improvement. TS will help a lot, Couch should be better, Blades and Ivey should be solid at least, and younger guys should get better with another year under their belt and better coaching.
All the guys at S are returning and some top (albeit young) talent might be able to contribute early.
Scheme
I'm in the camp that thinks after 5 years in the ACC other teams have now figured out how to play against Manny's defense. Sure, ACC teams with limited talent and/or no competent QB are ripe for getting run over by our attacking style. But as others have noted at great length, good offenses are now regularly beating this scheme, and better than good offenses are now embarrassing our scheme.
Our sack totals are a bit of a proxy for this. 2020 saw a sack rate of 2.7/pg, which is the lowest since Manny got here and down from 3.7 in 2019. This is in spite of having the two best DE's by far since Manny got here. It's an indication opposing OC's have figured out how to counter our pressure. And the problem with other OC's figuring out how to counter our pressure, is that it leaves us highly vulnerable once an offense play gets downfield.
OC's have figured out how to get the ball past our initial pressure, and that's a huge, huge problem for Manny's scheme.
Whether it's running behind or around our aggressive get-up-the-field, low gap integrity scheme like UNC did, or simply a dump the ball where our guys are blitzing from and/or a short spot passing game like NC State did, teams with competent QB's that don't operate at a significant talent disparity are no longer afraid of Manny's pressure defense and are performing well against us.
I don't see this changing in 2021. There's no reason it should imo no matter how much I might wish otherwise.
That's how I size things up for 2021, and how I come to the belief that things aren't going to much, if any, improved.
There are some things we could have done to improve our prospects for 2021, but we didn't do them. And that's highly disappointing because it's so unnecessary.