The Broncos have added 5(!) first round picks to the defensive line.
1. Von Miller - passing-down DE
2. Robert Ayers - moves from OLB to DE and passing-down DT
3. Brodrick Bunkley - a 2-down NT on this team; formerly a regular starter for a playoff team; widely considered an elite run stopper, but a bit of a 1st round bust because of a lack of pass-rush production (think Miller and Doom might help compensate for that?)
4. Ty Warren - DT; formerly a regular starter for a playoff team; unfortunately injured to start the season, though expected to return
5. Derrick Harvey - DE; like Bunkley, a solid run stopper considered a bit of a bust because of a lack of pass-rush production
Oh yeah, they also added some schlub called Doom at DE.
Now let's look more closely at the defensive tackles in particular. What has changed?
1. System change - the Broncos were previously pulling 2 to 3 players from this pool to play every down; now they will only be playing 1 (on passing downs) to 2. So we will see significantly less of these guys on the field.
2. Position change (Vickerson and Thomas) - Kevin Vickerson and Marcus Thomas will transition from 3-4 DEs to 4-3 DTs; both have previously played 4-3 DT with greater success than they enjoyed in the 3-4; if there is a weakness on the D-line, this is it, but from what little I could tell during the preseason, they seemed to be doing an adequate job.
3. Bunkley and Warren - These are quality starters. As long as one of these guys is healthy, at least one of the 2 DT positions on running downs is going to be taken care of.
4. Ryan McBean and Mitch Unrein - If these guys are playing significantly, there might be a problem, but even with the current injuries they will unlikely to see the field much; McBean was a starter last year and this year is deep depth; teams don't generally carry this many DTs, if injuries get this deep on other teams, they are bringing in guys off the practice squad.
All in all, a massive remaking of the defensive line. Will it perform better than last year? I think so, but only time will tell.