The Bears Defense Is Still “Really Good”

On the surface, it’s possible to make an argument that the Bears’ defense is still an elite unit. Their -5% DVOA has them as the 6th-best in the NFL. They have a sack percentage of 7.29% in 2019, compared to a sack percentage of 7.22% in 2018. That small dip represents a slip from 8th place to 12th place, but it still suggests that they are getting to the quarterback at a reasonable rate. Reassuringly, they have 3 sacks per game in 2019, the exact rate that they maintained in 2018. Likewise, the Bears are allowing opposing teams to convert 34.67% of third downs (10th in the NFL), which is comparable to the 34.91% rate allowed in 2018 (4th in the NFL).

So what’s the problem?

The problem is that the defense is no longer carrying the entire team, even as the team needs them to so this more than ever. The Monsters of the Midway had an unsustainable turnover rate last season, and they are--unsurprisingly--failing to sustain that rate this season. Take one obvious number. Chicago’s defense has allowed an 89.6 passer rating so far, 14th in the NFL; in 2018, they allowed a 73.2 passer rating, 1st in the NFL. The most important difference feeding into that number is a much lower interception rate. In 2018, the Chicago Bears forced an interception on more than 4.4% of the throws made by their opponents.

To put that number into context, Jay Cutler’s career interception rate was only 3.3%, and he was over 4.4% for an entire season only once. The 2018 Bears forced an astonishing turnover rate, and it led the league. Meanwhile, the 2019 Bears are intercepting only 1.75% of opponent passes (22nd in the league). Turnovers are fluky, and the Bears are another exhibit proving that they are not generated reliably on a year-to-year basis. Instead of almost 20% of opponents’ drives ending in turnovers, a little under 15% of drives are ending in turnovers.

Without those turnovers gifting the offense with field position, free points, and extra opportunities, the team as a whole is faltering.

Meanwhile, the defense against the run is also struggling. The 2018 Chicago Bears allowed only 4.1 rushing first downs per game, good for first in the league (the 16th team in the league allowed 6.2). The 2019 Bears have allowed 5.5 first downs per game, and that makes them the 16th team in the league. Likewise, Chicago is allowing more than 94 rushing yards per game (it was under 78 yards per game in 2018). That doesn’t seem like a huge difference. It’s just one play here or there. It’s one “if only” per half, or maybe even one extra missed tackle per game.

Exactly.

Defensive dominance is hard to sustain, because it only takes one or two lucky offensive plays, or one or two missed defensive steps, in order to break a game open. The rules favor scoring. The rules try to keep offenses on the field, and Chicago is obliging. Simply put, the defense went from allowing .28 first downs per play (1st) to .32 first downs per play (13th). How big of a deal is .04? The difference between elite and above average. That is how thin of a margin the Bears had.

Edge defenders like Khalil Mack don’t regress by suddenly failing to sack the quarterback at all; they regress by failing to sack the quarterback at the key moment. Interior linebackers like Danny Trevathan don’t regress by suddenly forgetting to tackle; they regress by allowing two extra yards before bringing the ball carrier down. Cornerbacks like Kyle Fuller don’t regress by allowing everything to be caught, they regress failing to pick off that one key pass, or allowing that one critical completion.

Eddie Jackson recently said that the Bears have lost their swagger. That might be a fair assessment of what happened. It might be more accurate to say that a defense cannot maintain that swagger indefinitely without help. The Bears defense is not a bad unit suddenly. However, that razor’s edge that made them elite has dulled just a bit.

Without any other help, “just a bit” is simply too much.

Unless otherwise noted, most statistics come from TeamRanking.com and Pro Football Reference.