Even though Phil Emery fired head coach Lovie Smith at the end of the 2012 season, he did everything possible to keep the defensive coaching staff in place. He lobbied hard to keep defensive coordinator Rod Marinelli on the staff because he was an integral part of the Bears' resurgence after the tough 2009 season.
Marinelli was one of the best defensive line coaches in football, and had done well as a defensive coordinator, but in the end his loyalty to Smith won out. Bob Babich moving on didn't come as a surprise because Babich married into Smith's family so there was instantly loyalty there.
The Bears did however manage to retain one key element to this defense, and that's the return of secondary coach Jon Hoke. Joining Hoke back in Chicago is defensive line coach Mike Phair who should help ease the transition, not for the Bears defense but for new defensive coordinator Mel Tucker.
Smith was oftentimes criticized for having a bland Cover-2 defense that some deemed outdated and too simple for today's NFL. However that type of assumption is not backed up by any of the analytics provided by the website FootballOutsiders.com. The Bears' defense since 2004 was dominant from in eight of the nine years that Lovie Smith was in charge.
To emphasize just how good the Bears defense was under Lovie Smith start with this section from FootballOutsiders:
Bears defense finished as a top-10 DVOA unit in eight of his
nine seasons (Table 2). Outside of the Ravens and Steelers,
teams are killing themselves to keep streaks like that going
after four seasons. Until last season, for example, the Bengals
had not fielded a top-10 DVOA defense over the course of the
entire DVOA era (i.e., since 1991).
Say what you will about Lovie Smith’s last stand, but his defense buoyed the Bears’ playoff chances in 2012, and it’s in a good position to continue that in 2013. The Bears had long been a team that ran a very standard defense, rushing the front four without many blitzes. But last year, they added a new wrinkle by turning superstar end Julius Peppers into a bit of a joker, moving him around the formations and trying to exploit mismatches. Much like everything else the Bears tried, it was very effective. Henry Melton, brought back on the franchise tag, is a three-technique with a ton of get-off who spends entire games in the backfield.
Finding a weakness in Chicago’s top-ranked run defense is an exercise in nit-picking. The team did its worst work against 21 personnel, but most of the problem there was the uninstinctual play of Nick Roach, probably the only starting 2012 Bears defender who could be declared “just a guy.”
That essentially sums up what the Chicago Bears defense has been, in phrase, nothing short of dominant year after year. It's a legacy that is going to be hard for Mel Tucker to carry, but perhaps a legacy he may only carry on for one more season.
The Bears will have a litany of free agents on defense the entire defensive front seven rotation except for Shea McClellin, Julius Peppers, Stephen Paea, Lance Briggs and the two new rookie linebackers. Peppers and Briggs could be cut due to their large cap numbers at the end of the 2013 season so there's only two likely to remain under contract. Virtually the same situation exists in the secondary with only safeties Chris Conte and Brandon Hardin under contract after the 2013 season.
What we could see is a complete turnover in scheme and personnel from one year to the next if the Bears falter this season. There may not be another situation in the NFL like it where a GM has set up his roster for a massive turnover. Even if Emery does turn around and try to keep players on board he may have a hard time doing so with so many players likely to hit the open market.
The key to this Bears defense has been their ability to run to the football and make tackles without missing tackles. To that end according to the FOA:
Once again, the Bears were very straight-ahead on defense, using either a 4-3 or an even nickel defense on all but 16 plays during the 2012 season. 6 Chicago allowed just 3.8 average yards after catch, best in the league. That included just 6.3 average yards after catch on passes caught behind the line of scrimmage, best in the league by almost a yard.
New defensive coordinator Mel Tucker is likely very happy with the talent the Bears have on offense now as compared to what he had last year in Jacksonville. The Bears are loaded with talent even with the loss of Israel Idonije the Bears' pass rushers are still some of the best in the NFL. The comparison between Chicago and Jacksonville borders on the absurd:
Between Peppers, Melton, and Israel Idonije, the Bears were spoiled with pass-rushing options before we even get to 2012 first-rounder Shea McClellin or the unheralded Corey Wootton. Wootton’s numbers may have been a bit inflated by the competition he faced.
Last season’s Jaguars pass rush was so bereft of talent that rookie Shea McClellin, who played just 35 percent of the snaps as Chicago’s fourth defensive end, would have been the best pass-rusher on Jacksonville’s roster.
As a result Tucker has moved McClellin around like the aforementioned Joker position that Julius Peppers played last year, lining him up as a linebacker, in the A-gap, outside standing up, down as a base 4-3 end. Tucker has shown a lot of new aggressive tendencies with this personnel and it should help to keep the Bears among the best defenses in the NFL again in 2013.