Whatever I tell you now is a lot more speculative than it's gonna be after spring/summer.
The reason is that here's what we need:
(1) Curtis Porter. Needs to actually be on the team.
(2) How much weight/strength does Tyriq Mccord gain?
(3) Does Eddie Johnson stay on the team?
(4) Does Kirby make a Pierre-like jump as a Sophomore MLB?
(5) Which young DB makes the jump? Bush, Jenkins, Howard or Crawford? If multiple players make a jump, things change quickly.
(6) Will there be an impact freshman that, maybe like AQM or Thomas, can be situational players? AQM could be a situational pass-rusher and Matthew Thomas could be a Nickel Backer who rushes or covers.
(7) The scary one is the uncontrollable one: how do injuries affect next year's defense?
What happens with all of those variables?
Assuming, pessimistically, that less than half of them work out well, I think we can still be a Top 50 defense. I know that's not amazing, but it's a big jump from what we saw last year. I don't think it matters as much what kind of defense we are statistically, but it matters what kind of defense we are in getting opponents off the field on 3rd down + what kind of scoring defense we are.
Here's why I think the jump will happen:
(1) The rotation will tighten up a lot. I think we saw a lot more guys playing when they shouldn't have been playing because the downside was limited and we needed to get guys on film.
(2) Instead of having DTs on sleds going backward, we'll have [hopefully] a 5th year senior in Porter and a 3rd year player in Pierre. I've written other posts about the big jump that usually happens with linemen in their 3rd years. They'll be backed up by a 4th year player and, instead of a bunch of True Freshmen, at least 2 guys who are in their 2nd year in College. Big deal there.
(3) I can't even guess what they're going to do with our LBs in pass coverage. They simply need to get better. They can't really be much worse. On talent alone, two of our better LBs could be two freshmen (Grace and Thomas).
(4) Our defensive backfield should be about a 7 on a scale of 10, up from a 4. We finally have Safeties with range. Even without range, they have enough athleticism to make up their bad angles.
Schematically
I don't think you'll see a lot of changes. What you will see, hopefully, is D'Onofrio trust his DBs more to mix in more man. I think you'll see *slightly* more blitzing. But, I don't expect the defensive sets to dramatically change from this year to next. We'll see.
