Switching to a 3-4: Is it the right move?

With Vic Fangio the new defensive coordinator for the Bears, the question arises: How likely is a switch from a 4-3 to a 3-4 base defense in Chicago?

New Chicago Bears defensive coordinator Vic Fangio has spent 26 years in the NFL as a coach, 14 as a defensive coordinator. During that time, Fangio has successfully run both 4-3 and 3-4 fronts.

His former head coach, Jim Harbaugh, said it best: “I think he’s one of the all-time best defensive coordinators in the history of the league. I think that’s who he is. I think that’s what his legacy will be someday.”

During his last four years as the 49ers defensive coordinator, Fangio ran one of the top units in the league. In four seasons, Fangio’s units never finished worse than fifth in total yards and 10th in points allowed. In three of the four years, the 49ers ranked Top 5 in both categories. The year prior to his arrival, the same defensive unit was ranked 13th in yards and 16th in points allowed.

It’s important to remember Fangio does have experience running a 4-3 base defense, particularly while he was with the Indianapolis Colts from 1999-2001. Yet he has spent most of his coaching career running a 3-4 base.

It’s also very important to remember the NFL is a passing league. NFL defenses run a sub-package (nickel and dime) on almost 60 percent of all defensive snaps, according to Pro Football Focus. Due to the prevalence of these sub-packages, which are primarily used on passing downs, the overall value of a base package has diminished.

Another underrated aspect of the impending defensive philosophy is head coach John Fox. Fox runs a 4-3 Under base scheme but has always featured star pass rushers in creative blitz packages. Starting with Julius Peppers in Carolina, then inheriting Elvis Dumervil and drafting Von Miller in Denver, Fox has used star pass rushers in exotic blitz schemes. He was able to implement this philosophy last year with Jack Del Rio, who leans 3-4 as well.

Both Fangio and Fox use similar one-gap philosophies. For example, Fangio’s defensive line featured three defensive linemen, two of whom weighed less than 300 pounds. On the flip side, Fox used Terrance Knighton in the nose tackle role, who weighs closer to 340 pounds. Over the last two years, both defensive units ranked in the top 10 against the run. This is very important when identifying which gap scheme can be a successful fit in Chicago.

4-3 Under

This was Fox’s base scheme in Denver. During that time, the SAM linebacker was their featured pass rusher. First it was Elvis Dumervil, followed by Von Miller, who served not only the SAM but also as a defensive end out of a two-point stance in the 50 front. Fox also featured both defensive tackles north of 300 pounds and a one-gap philosophy.

3-4 Over

Fangio came into San Francisco in 2011 and immediately implemented his 3-4 Over front. With that front, his unit featured his core of linebackers, while relying on his D-line to create the havoc necessary to free up the LBs. The 49ers carried only two D-tackles on the roster that were more than 300 pounds, while Justin Smith and Ray McDonald relied more on length and technique. Fangio’s scheme also shared a one-gap philosophy.

Common Themes

As Fox said in his opening press conference, good coaches scheme to their talent. That said, it’s no secret the Bears’ defense lacks talent. In last year’s draft, former general manager Phil Emery put an emphasis on the defensive tackle position with consecutive picks of Ego Ferguson and Will Sutton. It would be hard to justify putting both of those players, particularly Sutton, in unfavorable positions due to a switch to a 3-4.

- Both philosophies share a one-gap theme and an overall similar scheme, just different personnel.
- Aldon Smith and Von Miller: Both are premier pass rushers, both came from the same class and, most importantly, both played similar roles in slightly different schemes - outside linebackers that can rush from multiple spots.
- Importance of the safety position: Fangio had the pairings of Donte Whitner and Dashon Goldson, and Eric Reid and Antoine Bethea, while Fox invested in the position last year by signing top strong safety T.J. Ward to compliment Rahim Moore.
- Production of 10-sack players: Over the last three seasons, Fox and Fangio have combined to have seven defensive players with 10 sacks or more. In that same span, the Bears produced just two.
- Stopping the run: Since 2012, both units ranked ninth or better against the run.

Options to Ease the Transition

With multiple options on the table, Chicago’s defense is sure to see a makeover. Generally, a two-year timeline is needed for a full-on transition from a 4-3 to a 3-4, or vice-versa. Although a base front is usually run just 40 percent of the time, the personnel from that usually dictates the sub-packages and overall identity of the defense.

Ideally, the draft is where you build the foundation of any NFL team. Yet reality has reared its unsightly face for the Bears and Ryan Pace, who inherits a roster void of core young talent. To re-build the Bears in a timely fashion, free agency will be used.

Looking at the current roster, there are needs all over the defense but in order to make a transition that will fit the philosophies of both Fox and Fangio, two key positions will need to be addressed: linebacker and defensive line. These two positions will shape the identity of this defense.

Options to add through the draft, free agency and, even trade, will be out there. Familiar free agent names include S Rahim Moore, NT Terrance Knighton, S Parish Cox, CB Chris Culliver, LB Brandon Marshall, DT Ray McDonald and LB Nate Irving.

The 49ers, who are in serious salary cap trouble, also have bevy of top-tier linebackers like Ahmad Brooks and Patrick Willis, who will receive close to $8 million and up for 2015 and beyond. Former Niners safety Dashon Goldson, now with the Buccaneers, could also be a possibility if Lovie Smith doesn’t see him as a fit. All can be had through a trade or a surprising cap casualty.

The draft will also feature a pass-rush-heavy class, with names like Randy Gregory, Shane Ray, Dante Fowler, Vic Beasley and Alvin Dupree. Defensive tackles Leonard Williams, Danny Shelton and Jordan Phillips could also catch the team’s interest.

Will the Bears Move to a 3-4?

With their current roster and many needs on defense, a switch to a full-fledged 3-4 doesn’t seem very possible for 2015. Fox and Fangio share many similarities in philosophy and could end up collaborating together to feature a productive 4-3 base unit with hybrid looks.

Ultimately, don’t focus too much on the base front. Instead, pay attention to the types of blitzes and coverage schemes the coaching staff has up its sleeve.

The simple answer is: No. It’s reasonable to expect Fangio to keep the base a 4-3 for at least another season, albeit with numerous tweaks and adjustments.

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Aaron Leming has years of salary cap knowledge and has written for Rant Sports, Bears Draft On Tap, and Cover 32. He is a regular contributor to Bear Report.

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