Has Vanderbilt changed to a 4-3 defense for good or just to try to stop Georgia?

Adam Sparks
The Tennessean
  • For the first time in coach Derek Mason’s six seasons, the Commodores listed a 4-3 base defense on their depth chart this week.
  • Mason said it’s been a steady change to counter SEC offenses, and it began last season.

Did Vanderbilt alter its defense permanently or just to play No. 3 Georgia? Time will tell.

For the first time in coach Derek Mason’s six seasons, the Commodores listed a 4-3 base defense on their depth chart this week as they prepare to face the Bulldogs on Saturday (6:30 p.m., ESPN).

That seems seismic for a defensive-minded coach who has been linked to a 3-4 scheme since his time as Stanford’s defensive coordinator, beginning in 2011. Even Mason’s Vanderbilt biography page credits him as being the “architect of Stanford’s vaunted 3-4 defense.”

So why did Vanderbilt list a 4-3 defense to face Georgia? Mason said it’s been a steady change to counter SEC offenses, and it began last season.

“We have morphed that way (to a 4-3) as our conference has morphed towards playing 11-personnel (on offense),” Mason said. “When you start seeing spread personnel, it morphs you a lot of times out of a 3-4 structure.

“For us, if you’re playing 85 percent or 90 percent of your snaps in a 4-3 defense, that sort of changes the structure of what you are.”

What is a 3-4, 4-3 and 11-personnel?

A 3-4 defense means there are three defensive linemen and four linebackers, along with four defensive backs. A 4-3 defense means there are four defensive linemen and three linebackers, along with four defensive backs.

Offensively, a two-digit personnel package indicates how many running backs and tight ends are in the formation. A 12-personnel package means one running back and two tight ends; an 11-personnel package means one running back and one tight end; and so on.

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An 11-personnel package has become the most used in the NFL and, Mason said, has gained popularity in the SEC. An 11-personnel package also means there are three wide receivers in the formation, allowing for a more wide-open offense.

A nickel defense, meaning five defensive backs, often is used to defend a wide-open offense. One version of a nickel changes a 4-3 defense into a 4-2-5, meaning four defensive linemen, two linebackers and five defensive backs. Vanderbilt regularly used versions of the nickel last season.

Did Vanderbilt change its defense just for Georgia?

That coaching jargon sounds complicated. But Vanderbilt actually has used multiple defenses – 3-4, 4-3, nickel and more – during Mason’s tenure. The shift to using primarily a 4-3 could be permanent.

“That’s what we’ve tried to recruit to,” Mason said.

But the change could be more drastic for only this game. Vanderbilt started only two games in a 4-3 defense last season, against Arkansas and Georgia. It started in a nickel defense, usually in a 3-3-5, in seven games. And it started four games in a 3-4 defense.

Mason said a four-man front, either a 4-3 or 4-2-5 nickel, mostly was used during the games after the first play.

“I’m not saying we’ve totally gone to a 4-3,” Mason said. “I’m just saying that’s what our structure looks like most of the time.”

Can a 4-3 better contain Georgia run game?

Mason and defensive coordinator Jason Tarver also might be trying to simplify the responsibilities of their defensive linemen and linebackers in defending the run.

In most 4-3 schemes, players are responsible to fill one gap each; that is, the gap between each player on the offensive line. Many 3-4 schemes require each player to defend two gaps.

“One of our sayings is, ‘Multiplicity through simplicity,’” Tarver said, explaining the reason for using a 4-3 more often. “We can be in any front on any down.”

Georgia touted the SEC’s top rushing offense last season at 238.8 yards per game.

“(Georgia is) big, and they run the ball really well,” Tarver said. “For us, it doesn’t matter who we’re playing. Our biggest key will be straining to be right, straining to be in our gaps.

“We’ll be (in) multiple (defenses). But it doesn’t matter if you’re not straining.”

Reach Adam Sparks at asparks@tennessean.com and on Twitter @AdamSparks.