If 10 means I expect the D to be an elite unit and suffocate opponents to the point of embarrassment then I'm at a 6 for this D. On paper it looks like a special collection of players however, my voice of reason says pull back the optimism given the amount of players returning from significant injuries.
I like this scale system you propose.
On that basis, it's really hard to say as some pieces have to fall together.
DL - this is obviously the biggest question mark. It could go anywhere from 2-9 in my opinion depending on health, rookie, and 2nd year leaps (Chris Jones while not spectacular last year could generate more push with a solid presence in the middle)
DE - Solid starters, but depth can be an issue. Maybe Will Smith can be a solid rotational guy and keep Jones/Ninko fresher. I like this group, but give it a 7-8 (especially if Jones gets some respect from officials)
LB - still questions. If Mayo is back that makes then a 6 automatically, if Collins can be more consistent that may jump up to an 8 (given he can play roles on DE/LB/Coverage Safety, but is a LB and would only flex to those other positions for matchup advantages). so 5-8
DB - if Ryan makes a leap and Browner performs well, then this could be the best unit on the D. And that revis guy could make this a 10. Dennard -- probably is on the IR, but if he can stay on the field this will help and Arrington staying in the slot would actually help the D. so 5-10
S - We have McCourty and this can't be undersold. If Revis is able to lock up the island, that really gives McCourty less field to "theoretically" cover and that could make him very dangerous. But, who the heck is going to be the other safety? Harmon? Wilson, Chung, Ebner -- let's just say I'm hoping for a big surprise here and that someone steps up. so 5-7 is the range I give them
BB has some really flexible pieces here and can turn this defense into just about anything with the same group of personnel. That can be a pleasant thought. It will be interesting to see what he unveils and when.