I should have known this would invite comments about the SEC; I commented because I have a special interest in the UGA program (it's my 2nd alma mater). The point in me bringing that up is to say any opinions I have about UGA are automatically valid and unassailable.
Anyway, there's a nuance there, because "elite defense" - not something I said - could be different from "elite talent" and "elite coaching," which I did say.
Coaching: Kirby Smart is an Alabama legend and has already done incredible things for a 'bridesmaid' Georgia program.
Talent: currently ranked #1 class (247), #3 last year, #6 year before, and #6 before that with tons of talent concentrated on the defensive side of the ball. Also, Roquan Smith is the current Butkus winner
But I also think it's fair to say they have an elite defense. In addition to talent and coaching, even factoring in the 48 points (41 on defense) given up to the #1 P5 scoring offense in a Rose Bowl with overtime, they still gave up an average of ~15 ppg, having now played against 5 ranked teams. That's pretty good
Also, to someone else's comment, SEC may have pretty vanilla offenses but something about dominant DL and OL play can still lead to big points. Vandy gave up over 31 ppg; Kentucky, over 28 ppg. You could look at those numbers and think there must be a bunch of high-flying offenses in the SEC (there aren't, really).