Why LSU's new-look defense could make or break their season

It’s set to be a crucial year for Les Miles in Baton Rouge. He made it through an attempted ouster in 2015 and returns a lot of talent, making a successful 2016 a necessity for him to remain the LSU head coach.

There are certainly reasons for optimism. The Tigers return an offense that is largely the same as last year, only with more experience and maturity. They’ve had issues at quarterback, but Brandon Harris was better in 2015 than he was in 2014, and returns as an experienced starter. He has a talented group of wide receivers and a fantastic running back in Leonard Fournette to give the ball to. There will be changes on the offensive line, but their best lineman in 2015, OG William Clapp, returns.

However, the main reason for optimism at LSU is on the other side of the ball, with the arrival of defensive coordinator Dave Aranda from Wisconsin. He has a lot of talent to work with, as the majority of the key players from 2015 return. Aranda also brings a change of system, with the Tigers moving from a 4-3 to a 3-4.

In 2015, LSU had four down linemen on 75 percent of their plays under coordinator Kevin Steele; that figure was 85 percent in 2014 under coordinator John Chavis. Over the past two seasons, Aranda’s Wisconsin defense was a base 3-4, but spent more time in nickel than in any other formation, with only two down linemen and an extra defensive back on the field. So while most of the players will be the same, the roles they occupy will not, and that is particularly true for the defensive line and pass-rushers.

The true stars of Aranda’s Wisconsin defense were its outside linebackers, Vince Biegel and Joe Schobert — the second- and third-ranked players at their position in PFF grades last season, respectively. They were incredibly efficient as pass-rushers, amassing 18 sacks and 100 total pressures between them last season. Biegel rushed the passer more often, while Schobert was the more likely to drop in coverage. The table below shows how they won as pass-rushers in 2015.

At LSU those roles should be divided between Arden Key, Tashawn Bower and converted safety Corey Thompson. Key was a revelation as a true freshman in 2015 — his +24.1 overall grade was the highest posted by any freshman edge defender. He tied for fourth on the team with four sacks, but his 58 total pressures was a team-high mark. He’ll have to get used to rushing as a linebacker, and occasionally dropping into coverage, but the role is essentially the same, and he has the athleticism to cope with those differences. Bower’s role was more limited, but he still finished the season with a +10.6 overall grade and 19 total pressures. Between them, Key and Bower caused a huge amount of problems for Texas Tech in last season's AdvoCare V100 Texas Bowl, with a combined 19 total pressures.

The biggest challenge on the defensive line will be finding a nose tackle. Christian LaCouture played on the nose in the Tigers' four-man front, with Greg Gilmore backing him up, but neither finished 2015 with a positive run-defense grade, so they may not be the ideal options at 3-4 nose tackle, as that position requires even more strength at the point of attack versus the run. That said, both were better in 2014, with LaCouture earning a +5.9 run defense grade.

The Tigers reportedly tried out Davon Godchaux on the nose in the spring, but while he impressed as a pass-rusher in 2015, with six sacks and 42 pressures helping him to a +23.0 pass-rush grade, he fared less well against the run (-2.8 run defense) and isn’t an obvious solution to the problem. Whoever doesn’t stick at nose tackle should be an option at defensive end (Godchaux in particular), along with Lewis Neal (11 sacks and 48 total pressures) and Frank Herron (good run-defense grade).

Aranda has earned a reputation for creative blitzing, putting his best pass-rushers in advantageous positions. In 2015, 28 percent of the pressure generated by Biegel and Schobert was unblocked, compared to just 14.3 percent for Key and Bower. It will be interesting to see what he can achieve with LSU’s talented roster. How well the defense performs could hold the key to the Tigers' SEC and national title hopes.