Punch Drunk Wonderland

Which NFL Defensive Schemes Are Most Effective?

In the NFL the game is a constant evolving chess match between the offenses and the defenses. It’s a copy cat league, and new schemes that work are mimicked and tweaked. Offensive and defensive coordinators are constantly battling to find “the new thing” in an elaborate dance of strategic moves and counter moves. So, are there schemes that are statistical more successful than others? Our friends at numberFire.com have taken a look.

Even in such an offense-heavy era of football, there are many moments in NFL playoff history that have been defined by tide-turning defensive plays or stout stands against top-notch offenses.

We just saw Super Bowl XLIX ended by an astounding interception by undrafted rookie cornerback Malcolm Butler, and this isn’t an uncommon occurrence. In their run up to Super Bowl XLV, Packers’ defensive backs Tramon Williams, Sam Shields, and Nick Collins were instrumental in picking off Michael Vick, Matt Ryan, and Jay Cutler. Seattle Seahawks cornerback Richard Sherman saved the 2014 NFC Championship game for his team with an acrobatic deflection of a Colin Kaepernick pass.

So why do we know or acknowledge so little about these crucial players?

During the 2014 season, I did two studies on the differences in value via numberFire’s Net Expected Points (NEP) metric between certain passing and rushing schemes. I aim to do the same with defensive styles here. Over history, the look and roles of defenses have shifted, but it is still nearly impossible to win without a quality defense.

For our purposes, I’ve categorized each NFL team’s defensive scheme in two ways: defensive front and style of coverage or gap responsibility. In the following sections, we’ll see how each has performed historically in the last 15 years by NEP, which is a measure of real production on the football field. This metric assigns an expected points value to each play from scrimmage based on how it advances a team’s chances of scoring, thus giving us a better sense of how each play and player contributed to the team. What schemes have been the most successful, then?

Green Eggs and Slam: Defensive Fronts

First, let’s look at the modern base defensive fronts: the 3-4 and 4-3. The names of these schemes come literally from their alignment; the first number being the typical amount of down linemen, the second being the stand-up linebackers. The 4-3 was the next step out from the 5-2 and 6-1 formations, and the 3-4 emerged a bit later as a way to get even more quick, athletic players on the field at one time. There are various ways to align these defenses and tweak them for different purposes, but we’ll get into that later. For our purposes, also, the hybrid defenses like the Buddy Ryan “46” or Belichick hybrid package are considered 3-4 base.

Most football fans see this base defensive alignment as the primary driver for defensive difference, but is there that much difference in production? The table below shows the average Adjusted Defensive NEP (adjusted for strength of opponent) for each base defense below, as well as their production in Adjusted Defensive Passing and Rushing NEP separately. Remember, with defensive versions of NEP, the lower (or more negative) the number, the better. What do we find?

Style Adj. D NEP Adj. D NEP/P Adj. D Pass NEP Adj. D Pass NEP/P Adj. D Rush NEP Adj. D Rush NEP/P
3-4 15.58 0.01 20.12 0.04 -4.05 -0.01
4-3 4.05 0.00 12.65 0.02 -8.03 -0.02

There is a slight, yet noticeable, difference between the results gained between the two base defenses. The 4-3 limits offenses by more than 11 points fewer than the 3-4 scheme in the overall Adjusted Defensive NEP. While not drastic, it is worth mentioning that the 4-3 gives up little more than a touchdown and a field goal less than its counterpart, historically. On a per-play basis, they are nearly identical, but the 4-3 still limits each phase by a minimum of 0.01 NEP per play compared to the 3-4.

Continue reading at numberFire.com… (@numberfire)


K. Smelser About K. Smelser
Kelly Smelser is Owner/Senior Writer for Punch Drunk Wonderland and PDFantasy Sports. Architect of the PDW fantasy football world and general spinster of NFL and Fantasy Football news and analysis. Long walks on the beach, sunsets, and other such niceties are also fine...