Fullbacks are gradually being phased out of base offenses in the NFL, replaced by tight ends and slot receivers. Defenses, whether they are a 3-4 or a 4-3 base, have seen this change, but have they adapted to the speedier offensive personnel that is more likely to catch passes?

Defenses Used by NFL Teams

For that fullback migration, it was a clear picture of one position morphing into others. With defenses, the picture is a little muddier and it’s easier to look at the combination of down linemen-linebackers and how the number of teams using a specific combination has changed over time.

In 2008 when nearly half of the teams in the NFL were using a fullback as part of their base offense, the 4-3 defense was the defense of choice for 23 teams, with the remaining nine opting for a 3-4 look.

As the move away from a fullback and towards a second tight end began in 2009, a couple extra teams started running 3-4 defenses and two teams started playing most of their defensive snaps out of a nickel package (The Green Bay Packers opting for a two down-linemen approach where the Minnesota Vikings went with the more traditional four down-linemen with two linebackers).

Those trends continued in 2010 and became even stronger in 2011 (the height of the two tight end offense), when the number of teams to run the 4-3 dropped to 13 and we see the first instance of a team running a dime defense as their most often used set (the Buffalo Bills).

With the slot receiver now in vogue in 2013, defenses have been forced to run more nickel than ever. Half of the NFL has a “base defense” that has an extra defensive back in it.

Eleven of those have four down lineman and two linebackers with a nickel defender. Only six teams run a 4-3 set most commonly, a 74 percent decrease since 2008.