I think, what a lot of you guys are touching on, at least, is who plays and where, basically, and how long does it take for everyone to adjust to both a more pass-heavy offense and a completely new defensive front.
I think our secondary is fairly well settled, due to there still being a high number of upper classmen starters there. Same with RB, where we have three guys in order just like last year. After that, though, it gets extremely questionable predicting who the starters will be.
The GOOD news is, we actually have high quality depth at every single position. We have tons of LB's, WR's, and offensive and defensive linemen to work with. A lot of them are young, sure, but the talent level has been upgraded significantly over the last few cycles, plus the sheer depth involved (particularly at LB and OL, where we will finally, FINALLY have a 2 deep rotation if we want it) should make it dynamic, flexible, and exciting.
The downside of all of the above though is obviously the lack of experience, and the new scheme being learned on defense.