Check out this excellent 2009 Auburn recap and 2010 projection from Team Speed Kills.
The only thing I'd add would be to note that the '09 defense's real problem was plan old depth, or rather a severe lack of it. By the second half of the season, there just weren't any backups in the defensive backfield, thus playing the same three linebackers for entire games. That led to an awful lot of second-half points, costing the Tigers leads (and games) against Kentucky, Georgia and Alabama.
With just a couple of role-players--not stars, mind you, just guys who could fill in for a series or two to spell the starters--at linebacker and safety, AU had a serious shot at finishing 11-2. Without them, 8-5. Whether they'll be there this year... well, we'll see.