Last year, the Alabama defense let up 8.2 points-per-game (PPG), which was the best defensive showing—in terms of PPG—in the BCS era.
In fact, the only other AQ team since 1998 that has allowed fewer than double-digit points per game was the 2002 Miami Hurricanes.
In effect, it will be difficult for Bama, or any team, to top last year's performance.
Nevertheless, there will be plenty of good defenses.
That said, the following is not an attempt to predict which teams will wind up as the top 25 scoring defenses at the end of the college football year.
For example, it is a given that Florida International and will wind up amongst the top 10, but are the Golden Panthers really one of the top 25 most feared defenses in the country, let alone amongst the top 10?
It is safe to say, "no."
Ultimately, strength-of-schedule factors into the PPG quotient. In effect, this list will focus on which teams will field the toughest defenses in 2012, regardless of schedule or what their final PPG looks like.