For all of you people that think a team can't rebound in one year, just watch the Cincinnati Bengals in 2009. Now that Rivers is back, you can imagine their D to be pretty legit. Adding Rey Mauluaga* to the mix doesn't hurt either.
Losing Carson Palmer last season was the key factor in the Bengal's poor season. Adding Andre Smith helps out the line, but I still don't know if that is enough to keep Palmer off of his back.
You can't contend in a game without a running game. I'm not a strong believer in Cedric Benson. A few free agent RBs wouldn't hurt much. Even if they didn't get as much playing time, it could push Benson to play at a higher level.
Assuming the line does their job, and the run game clicks, there is no reason for the Bengals to miss the post season.