It's no secret that the Auburn defense has struggled mightily over the last two years. In 2011 they finished 11th in the SEC in scoring defense and in 2012 they finished 10th. In 2011 they finished 11th in total defense (408 ypg) and in 2012 they finished 13th (420 ypg). When Gus Malzahn was hired in December he brought in SEC veteran Ellis Johnson to install the 4-2-5 defense.
The 4-2-5 is commonly referred to as a nickel defense. It utilizes four down linemen, two inside linebackers and five defensive backs. They key to the formation is the fifth defensive back which some refer to as the STAR. This player is typically a combo LB/S who has size and speed. South Carolina has had success recently with guys like Antonio Allen and Devonte Holloman playing this position. A player like Alec Ogletree is somebody who would fit well in this position.
Johnson wants Auburn's four down linemen to get after the quarterback as their first priority. Auburn has recruited very well on the defensive line over the last few years but they are losing their best player to the NFL Draft (Corey Lemonier). It sounds like the defensive line will be asked to do a lot of similar things that Brian Van Gorder asked them to do last year, which is primarily to get penetration. The talent is plentiful in this area for the Tigers and new defensive line coach Rodney Garner hopes that competition will bring the best out of the Tigers.
Auburn has been known for their smallish linebackers but with this new scheme they need bigger stronger players at the ILB position. Right now, there aren't a whole lot of players on Auburn's roster that fit the mold that Ellis Johnson is looking for.
Much like at LB, the type of player that Auburn is looking for (tall and lengthy) at corner aren't plentiful on Auburn's current roster. Auburn will use three safeties in their base defense with two of them providing a great deal of run support so they will need to be big and physical. This is one position in the back seven where Auburn does seem to have the bodies that fit the mold and there should be some good competition in spring practice and in fall when the new freshmen arrive.
In year one of the Ellis Johnson defense at Auburn it's going to be about tweaking and experimenting. The new defense will be installed but it will also have to be tweaked based on the personnel that Auburn has to work with. Right now, Auburn simply doesn't have the personnel to effectively switch 100% to a 4-2-5 and I think they will continue to struggle on defense in 2013 because of that reason. Auburn fans should look for improvement and hope for the best but they need to realize that this will be a rebuilding year for the defense.