Advanced Defensive Stats: S and LB Pass Coverage

| June 30th, 2021

Let’s continue our quick tour of Chicago’s defense by honing in on pass coverage.


At a surface glance, Chicago’s pass defense was just about the definition of average in 2020. They gave up 64% completion (14th in the NFL), 7.2 yards/attempt (16th), 28 touchdowns (16th),  had10 interceptions (23rd), and allowed a passer rating against of 94.9 (20th). They were 21st in Pro Football Reference’s Adjusted Net Yards/Attempt, which accounts for sacks, touchdowns, interceptions, and yards, and 13th in Football Outsider’s pass DVOA rankings, which is intended to be a one-stop measure of pass defense overall.

A closer look at advanced statistics from Next Gen Stats shows how QBs playing against the Bears played relative to the rest of their games and the NFL average.

A few thoughts:

  • Opposing QBs generally didn’t see any change against the Bears in terms of how long they held the ball before throwing it. This means that Chicago’s pass rush wasn’t forcing them to get rid of the ball quickly, but also didn’t let them hang onto it forever. Again: average.
  • In terms of where QBs threw the ball against Chicago, opposing QBs typically threw it slightly deeper against the Bears than other opponents, though the difference is pretty subtle (for context, individual QBs ranged from 5 to 11 yards for average pass depth). That small difference was completely eliminated when looking at average completion depth.
  • Opposing QBs also threw into tight coverage (aggressive throws) slightly more than normal against the Bears, though again that’s not a huge difference. For a little context, individual QBs on the year ranged from averaging 11% to 22% on aggressive throws.

Now that we’ve firmly established the overall pass defense was around average, let’s look at how individual players fared in coverage last year to see where Chicago might have strong and weak spots. We’ll go position by position, using advanced data from Pro Football Reference.



Let’s start at linebacker, where Roquan Smith and Danny Trevathan were remarkably different in coverage. The table below shows the number of targets each player was in coverage on, as well as how many yards/target they gave up when targeted. Rank compares them to all linebackers, based on this study I did last offseason.

A few thoughts:

  • Hello Roquan Smith! The top 10% doesn’t really do him justice there, as the cutoff for top 10% of all LB was 5.4 yards/target. Roquan’s value there is more than half a yard better than the next best LB season in Pro Football Reference’s database (min. 40 targets), which goes back to 2018. His outstanding coverage abilities were the primary reason Smith was named a 2nd team All Pro in 2020.
  • On the other hand, we have Danny Trevathan, who was every bit as awful in coverage as Roquan was outstanding. Again, bottom 10% doesn’t really do him justice, as the cutoff there is only 8.5 yards/target. This was the 3rd worst mark of any LB season (min. 40 targets) since 2018.
  • I’ve heard some people say Trevathan started the season off poorly but got better as it went on, but unfortunately the stats don’t back up that theor. If you split up his 16 game season into 4 game samples, Trevathan allowed 12.8, 8.8, 8.7, and 9.6 yards/target in the 4 samples. He also gave up 8.8 yards/target in 2019. At 31 years old, this seems like a trend that is unlikely to reverse. Unfortunately, Trevathan might just be washed up.



Now let’s move on to safety, which like linebacker returns basically the same personnel as 2020. The table below matches the linebacker one above, only positional norms are different for the ranking. The median value is provided, but again you can look here for the full range.

A few thoughts:

  • Eddie Jackson’s coverage production took a nosedive in 2020. After 2 straight years of giving up less than 6 yards/target and ranking in the top 20% of safeties, he fell to below average. Given that his expensive new contract is just kicking in for 2021, and the Bears have already restructured him to push cap hits to the future, they have no choice but to hope 2020 was an aberration. Jackson is only 27, so there’s no real reason to think he can’t bounce back nicely. Kyle Fuller was in a similar situation heading into 2020 (a down 2019 after really good 2017 and 2018 seasons), and he recovered very nicely. I expect Eddie Jackson will do similarly.
  • Tashaun Gipson’s production also took a dip in 2020. Between 2018 and 2019, Gipson gave up an average of 7.6 yards/target, which is slightly above average for safeties overall. The consistent struggle of both starters in 2020 makes me wonder if it was a scheme thing, and perhaps new defensive coordinator Sean Desai (who has a background working with safeties) can help.
  • I included the top 2 backups because they’re both back in Chicago, but neither has a large enough sample size to draw much conclusion from. Deon Bush has been consistently impressive in small samples over the last 3 years though; giving up an average of 5.9 yards/target on 24 targets (including postseason) between 2018-20. He seems like a good backup to have around.


Wrap Up.

I will save cornerbacks for a different article since that position has significant turnover, which calls for a deeper dive. When looking at linebackers and safeties, Roquan Smith is an absolute stud, Danny Trevathan seems to be washed up, and Eddie Jackson really needs to have a bounce back year in 2021, which he should be able to do.

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