This is a useful reference from the 2018 preview summarizing the Nick Saban defense that has made it’s way around the league. The Dawgs lean on this the most.
It’s a copycat league, and for the most part, teams are taking the Nick Saban, Rip/Liz scheme and running with it. Look anywhere you want - South Carolina, Auburn, the Dawgs, even Clemson in the ACC- they all use it as a means of defending spread zone running attacks.
The idea is pretty simple:
The defense identifies the side of strength for the offensive alignment, and rotates a safety down into the box just ahead of the snap. The front 7 all have gap responsibilities and the extra body puts the numbers advantage in favor of the defense. It isn’t foolproof though and, if the offense has the matchups, it can be exploited.
Thus far in the CKS era the defense has gone through a revolving door of deficiencies.
Lack of a bonafide space-eating nose tackle, inexperience in the secondary, poor run fits and lack of athleticism in the linebacking corps, and lack of integrity in setting the edge from the outside linebackers and defensive ends.
At long last, we might see a season without any of those in 2019.