Comparing the Defensive Approach of Dennis Allen and Matt Eberflus

The Chicago Bears changed out Matt Eberflus for Dennis Allen as the man calling defensive plays this offseason. Both men run a base 4-3 defense, with 4 defensive linemen and 3 linebackers, but their defensive styles are quite different. Today, I want to dig into the data to see what we can expect to see stay the same or change quite a bit compared to Chicago’s 2024 defense.

Personnel

Let’s start with a basic look at how many players from each position are on the field each snap. The table below shows that data for both the New Orleans Saints and the Bears across the 2023 and 2024 seasons (data from Pro Football Reference).

A few thoughts:

• Let’s start with the one clear similarity: both coordinators like to pull a DT off the field and replace it with a DE roughly 20% of the time (as evidenced by 2.2 DE/snap and 1.8 DT/snap instead of the assumed 2/snap in a standard 4-3 look). That presumably happens on passing downs to help provide some extra pass rushing juice.

•I will be curious to see if that trend continues in Chicago this year since Chicago has significantly better depth at DT than DE. It’s highly possible the Bears decide that leaving 2 of Grady Jarrett, Gervon Dexter, or Shemar Turner on the field gives them a better pass rush than replacing one of those with a backup DE like Austin Booker or Tanoh Kpassagnon.

• One clear difference is in the number of LB on the field. Eberflus’ defenses use more of them.

•The Eberflus defense was extremely vanilla in 2024. They played only 16 snaps that were not in a base (4 DL, 3 LB, 2 CB, 2 S) or nickel (4 DL, 2 LB, 3 CB, 2 S) look. Those were their 2 packages, and they ran nickel roughly 80% of the time, which is why they averaged 2.8 CB (2 CB in base, 3 in nickel) and 2.2 LB (3 LB in base, 2 in nickel) per snap.

•Allen’s defense will use a lot of different looks in sub packages, which is why the LB, S, and CB numbers are different from Chicago’s. For starters, they run a lot more dime packages, where they have now 6 DBs on the field, usually to go along with only 1 LB. This was Allen’s base defense on 3rd down in 2024, and has been heavily used against pass-heavy teams going back to at least 2020. We have already heard reports from camp that Chicago’s defense is utilizing dime packages significantly more than they did the last few years, and we should expect that to continue into the regular season.

•We can tell from the S and CB data that sometimes the extra defensive back in dime looks is a safety, while other times it is a CB. Notice Chicago was at exactly 2.0 safeties/snap, while NO was above that, indicating they had a 3rd S on some plays). I...