The Bears’ big strength in the four years of Matt Nagy’s stagnant offense was the defense formed by Vic Fangio and continued under Chuck Pagano and Sean Desai.

Desai took the Bears back to the top 10 this year after a slump last year when they finished sixth overall despite dropping to 23rd against the run.

With the arrival of a new head coach at Halas Hall, it is possible that their one great strength will be drastically altered. A head coach on the defensive end might want an entirely different roster. An experienced attacking coach might want to go back to an old defensive system used by his former teams or might have defensive assistants in mind who would play a different style of defense.

The Bears went from the 4-3 defense they had played since the late 1950s to a 3-4 look in 2015 and finally perfected it in 2018 under Fangio. The current search for a head coach could affect whether they stay on this path or return to a 4-3.

If that happens, the impact could be greater up front and at linebacker, as different types of defensive linemen are needed to execute the 4-3 than the 3-4, and different types of rushers to edge are also required.

They need more linebackers because they get by with two and sometimes one inside linebacker. A 4-3 would require a weakside (Will) and strongside (Sam) linebacker to accompany the Mike on the inside. There just aren’t enough regular linebackers on the roster right now and they’d have to spend free agent money or a draft pick to fill that position.

The Bears would be fine with Roquan Smith inside, regardless of the system. He’s not as big as some of the classic 4-3 middle linebackers, but big enough. Sometimes he plays the only linebacker position in their current defense, anyway. At 6-foot-1 and 232 pounds, he’s taller than Hall of Famer Mike Singletary and he’s got the speed to get through the cover zone much like Brian Urlacher did, even without the height. that Urlacher had.

On the edge, it wouldn’t affect Robert Quinn. In fact, he would probably like it because he was a 4-3 player when he came to the Bears and had to adapt. Trevis Gipson was a 4-3 college winger and had to adjust to a new position and he wouldn’t mind. As for their lead passer, Khalil Mack’s last three years and biggest sack season came when he was playing end of Oakland’s 4-3 rather than outside linebacker in a 3-4. It would therefore seem that the Bears are installed in this position despite everything.

Another change could occur if they bring in a coach with man-to-man coverage tendencies on the zone. The Bears have been synonymous with zone coverage since Lovie Smith was a coach, although Vic Fangio’s zone style is very different from the shell appearance the Bears used in their last run to a Super Bowl. They would need more defensive backs with strong man-to-man coverage skills like Jaylon Johnson possesses, although they really need help in that regard anyway.

A number of defensive coaches might want more of a safety look than the Bears have deployed since 2015.

Here’s how the candidates could impact what the Bears do on defense.

Todd Bowles

Tampa Bay’s defensive coordinator uses a 3-4 with similar sized players to what the Bears have. The biggest real differences would be requiring more man-to-man pass coverage and also needing the help of an inside linebacker with the ability to blitz. The Buccaneers led the NFL in blitzes with 40.8% defensive snaps. The Bears were just 21st at 22.6%. Bowles loves disguises in the high school, but it’s something the Bears have done from day one. They would just become more of an offensive and play defense with Bowles.

Doug Pederson

As a rookie on the offensive side, his defensive approach wouldn’t necessarily be critical and he could hold on to what they’ve been doing. However, he went 4-3 in Philadelphia and they used some rather distinct techniques. Their defensive coordinator was Jim Schwartz, him from the wide-9 look to the point. Trevis Gipson could look good in a wide nine approach. It’s hard to say how Khalil Mack would fit in, but again Mack is so good it’s hard to see him failing in any scheme. Schwartz used more man-to-man coverage than the Bears. And, coincidentally, Schwartz would be available to become a defensive coordinator as he currently only has a senior defensive assistant role with Tennessee.

Brian Flores

Figure on something straight out of the Patriots handbook because it came out of the Bill Belichick system. The Patriots used both 3-4 and 4-3, but Flores had them at 3-4 with plenty of nickel coverage. What they really did more than anything else was blitz and man-to-man coverage like the Patriots have so often done. They blitzed about a third of the time.

Dan Quinn

Quinn oversaw the Legion of Boom in Seattle and enjoys 3 zone coverage or man to man coverage. The Bears are currently playing a lot of cover-3s anyway. Quinn’s defenses were known for four-fronts, so the edges would face changes. But as mentioned, their top three edges seem suitable for playing either the 4-3 end or the 3-4 edge.

Matt Eberflus

He changed the Colts from a 3-4 defense under Pagano to a 4-3 defense, and if hired, he could be expected to do the same in Chicago. The change Eberflus experienced with the Colts is not in training but in coverage. He started with strong coverage area 2 tendencies and adapted coverage 3 as the Bears use it extensively, but also blended in a unique safety look. The Bears aren’t big on that at all. The most affected players could be Mack, if he comes from a low position, and also Eddie Jackson because the Bears rarely use the single-high much.

Leslie Frazier

Frazier’s base is 4-3 and he’s been exposed to a wide variety of approaches over the years, from being a follower of Jim Johnson and Tony Dungy, to a player under Buddy Ryan. He seems to have opted more for a more conservative approach with zone coverage and less blitzing. The difference could be in defensive/finishing tackle. The Bears deploy 330-pound Akiem Hicks and 302-pound Bilal Nichols at the end. They have always relied on bigger inside defensive linemen. The Bills have some 280 pounds to fill the gaps rather than relying on a two gap approach. Additionally, the Bears would need to bring in a few inside linebackers who can both cover and play the run. They need to add inside linebackers anyway, but they need them even more for a 4-3 approach. The Bears may need more of a box safety at the solid safe position they go with him.

Dennis Allen

His base is 4-3, but the Saints are rarely there and, just like with the Bears’ defense, their tendency now is for nickel or dime coverage with a run four. The difference is the type of players. They don’t rely as much on massive inside line defenders like the Bears. It may need to acquire a few leaner, quicker defensive linemen and a linebacker who excels at pass coverage. The Saints will leave more of their defensive backs on an island, so better man-to-man DB coverage would be needed. Allen has become a bit less of a blitzer this year, hovering around the top 10 blitzers this year, even blitzing less than the Bears. They would rather not blitz as much, but they had to to improve their passing rush.

Nathaniel Hacket

Although he is an offensive coach, he has his back on defense because he is a big believer in the running game. The Packers’ offensive coordinator has been with two teams that had strong, aggressive 3-4 defenses – the current Packers and the 2017 Jacksonville Jaguars. Keeping Sean Desai as defensive coordinator and maintaining the status quo might be best served with Hackett on board.

Jim Calwell

He was never much associated with a solid defense, although it should be noted that the first Lions team he coached had the league’s No. 2 defense when Teryl Austin was defensive coordinator and No. 1 against the race. Their focus revolved around a 4-3 with a cover-2 from Tony Dungy’s background. Austin is once again available to be coordinator. He’s in Pittsburgh coaching defensive backs.

Byron Leftwich

It’s hard to determine what Leftwich would do defensively as an offensive coordinator who doesn’t even have much experience in that area, but as such he would look best to keep Desai and the status quo.

Brian Daboll

Although an offensive coordinator, Daboll has extensive experience in the New England formula for success and spent a season at Alabama under Nick Saban, who qualifies as a college version of the Bill Belichick move. You’d think some of that defensive man-to-man approach with a hybrid style up front has rubbed off on him. It’s still hard to say but if he hires a defensive team from what he learned in Buffalo, it might be more 4-3.

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