Self-Scouting Chicago’s 2018 Defense: Run & Pass Across the Field

| June 24th, 2019

Chicago’s defense was awesome in 2018. We all know this. They finished 3rd in yards, 1st in points, and 1st in turnovers. So let’s take the same approach we did with the offense and look at how they did defending different areas of the field. All statistics come from the NFL Game Statistics and Information System or Pro Football Reference’s Game Play Finder.

Run Defense

Chicago’s run defense was fantastic in 2018, finishing 1st in yards against, 4th in yards/carry allowed, and 1st in touchdowns given up. Now let’s break it down by different areas of the field to see if there were any weak links.

Here’s the data for Chicago’s rushing defense in 2017.

  • The line at the bottom is the line of scrimmage, runs are split into 7 zones, and attempts and yards per carry are listed for each zone, with ranks relative to the rest of the NFL in parentheses.
  • The height of the bar is proportional to yards per carry, and bars are colored green for top 10, red for bottom 10, and yellow for middle 12.
  • Note expected yards per carry varies by region, so the colors are relative to their peers in that region.

A few thoughts:

  • My goodness, that is beautiful. Their run defense was consistently among the best in the NFL pretty much everywhere. It didn’t matter where teams tried running on the Bears, they weren’t going far.

  • For the 2nd year in a row, their worst area was outside runs to the right. Last year, I primarily blamed that on Kyle Fuller, who led the NFL in missed tackles, but he only had 6 missed tackles in 2018 according to Pro Football Focus, so I don’t think that’s fair this time around. The run defense there improved from bad to average in 2018 (possibly because Fuller missed 15 fewer tackles), but they still gave up 8 runs of 10+ yards on only 40 carries, which is decidedly not good.

Pass Defense

Likewise, Chicago was really good defending the pass in 2018. They were 7th in yards allowed, 1st in yards per attempt allowed, 3rd in sacks, and 1st in passer rating against. Once again, let’s look at how well they defended different zones of the field to see if there were any weak links.

Here’s the data for Chicago’s passing defense in 2017.

  • The number of plays, completion percentage, and yards per attempt are given for 6 zones.
  • Each zone is colored according to the average of the yards per attempt and completion percentage (green = top 10, red = bottom 10, yellow = middle 12).


A few thoughts:

  • Defense to the outside was consistently excellent, a stark contrast from 2017. One similarity from 2017, however, is that the right side was a bit better than the left despite more targets being aimed at the right. Last year I hypothesized that was due to Kyle Fuller (right side) outplaying Prince Amukamara (left side), and this year I have data to check that. According to The Quant Edge, teams averaged 7.2 yards/attempt throwing at Fuller and 9.0 yards/attempt throwing at Amukamara. Those numbers were 6.3 and 7.5, respectively, in 2017, showing that Fuller has been consistently excellent when targeted for 2 years now. I still don’t understand why teams keep throwing at him so often. He saw 111 targets go his way last year, compared to 84 for Amukamara.
  • The Bears weren’t great defending the middle of the field, though the completion percentage they allowed was good. That must mean that they gave up a number of big plays in that area, and sure enough there were 18 plays (12%) that went for 20 or more yards, including 5 for 48 or more.
  • The defense in the short middle was improved significantly from the bye week, which I hypothesized would happen. Part of that is due to Roquan Smith growing up, and part of it is due to the defense getting a bit better playing from ahead without giving up too many chunk plays underneath.

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