While I do not agree at all with the ranking, and think that Auburn will have at least 4 losses this year, I do think the defense will be improved... and not because of Muschamp... but because they get some injuries back. Lawson will be a factor on the line, along with Cowart. Hell, they can't be any worse, right? I think the LBs and Secondary will still be awful and unable to tackle, but the DL should be improved.
As for offense, JJ is likely better that what they have had since Cam, and the RBs should not see a drop off (at least not much). WR takes a hit losing Coates, because if nothing else, he could spread the field for other WRs.
Do I think they are in play for the SEC title and the playoffs? Not at all. I think they will lose to Louisville, LSU, UGA, and Bama.... and may even drop their road game to Arkansas. If they come out of this season with less than 4 losses, I would call that a success in their books... but it does not merit a #2 ranking.
Muschamp is at least a year and half away from turning that D around... and he won't be there that long.