I don't agree with 8-8, but I'll take a stab at it.
No LBers. The best LB this preseason was probably Brooks Reed. Cushing is going to have some problems getting back to form, and that injury does take time to come back from. Remember Ryans didn't start to play like himself until late in the season. Willie Jefferson is a nice rookie, but he's still a rookie, and raw at that.
OL - I think the OL is going to be as bad as it was last season. That doesn't necessarily equate to more losses right off, but it does make it harder for them to be effective on offense, especially in the red zone. Ben Jones is not good and Newton is somewhere between bad and awful at pass pro. Brooks at RG might be a beast in the run game, but he's going to have some problems in pass pro as well.
Schedule - I think this year's schedule is tougher. '49ers, Seahawks, Pats, Ravens, and Broncos are all among the top 3 or 4 teams in their conference. The Colts are never an easy game, and Luck will be that much more seasoned when he faces them.
Schaub - sorry, I know some will disagree with me, but the guy is an issue. He's been off target thus far in the preseason, and last year's late season slide has done nothing to bolster my confidence in him. After 2011, everyone said the Texans were one Matt Schaub away from winning the Super Bowl. Well, the 2012 Texans got their Matt Schaub and there wasn't much difference in the end. He'll put up his usual stats, and they'll be just as useless as they've always been. Moving the ball between the 20s and settling for FGs seems to be what Schaub (and Kubiak) excels at. If Foster can regain his 2011 form, then some of those FGs become TDs, and that will matter. But because of the aforementioned OL, I don't see that happening, and then it falls to Schaub.
Safety - Manning is solid. After that, you have a 35 year old safety with a blown out hip that couldn't tackle last year, a rookie that hasn't proven to be ready for prime time just yet, and a special teams try hard guy that just can't quite cut it at the position. Oh, and a second round bust at CB being moved to safety to see if he can be salvaged. And Eddie Pleasant.
All that said, I reiterate that I don't buy 8-8. I could see 9-7 if a key injury or two happened (*knock wood*), but 10-6 seems more likely to me, and that should be good enough to win the division. 11 or 12 wins is feasible if the aforementioned concerned prove to be unfounded.