Advanced Defensive Stats: CB Pass Coverage

| July 1st, 2021

Finally, let’s end with a look at the cornerbacks, who will have some personnel changes from 2020. Gone are veterans Kyle Fuller and Buster Skrine, while Desmond Trufant has been brought in to compete with a host of late round picks from the last few drafts.


The table below shows 2020 coverage stats for all 2020 Bears and Desmond Trufant, who was in Detroit last year. The * for Vildor and Shelley indicates that I included their playoff stats to increase their sample size, since they only played the last few games of the regular season. The rank compares their yards/target mark to all NFL CBs. The median value is included on the bottom, but you can view the full data here.

A few thoughts:

  • Losing Kyle Fuller, who was a cap casualty this offseason, is a massive blow for a secondary that was already full of questions. He was the best player in the secondary by a wide margin last year, and his departure leaves a cornerback group with nothing but questions.
  • However, there are some reasons for optimism among the cornerbacks, if you look closely enough. Desmond Trufant was very good in 2018 (6.2 yards/target) before struggling through injuries the last 2 years. He’ll be 31 at the start of the season, but maybe he can buck the odds, stay healthy and regain his prior form.
  • At nickelback, losing Skrine isn’t actually a problem, as he was not good last year. Skrine missed the last 5 games of the season (including playoffs) in 2020, and Duke Shelley stepped right in and matched his production.
  • Of course, that’s not to say Shelley was good, as he also ranked below average in yards/target. However, if you want to be optimistic, you can point out that Shelley was pretty solid outside of getting torched by Justin Jefferson in one game against Minnesota. In that one game, Shelley gave up 101 yards on 8 targets (11.2 yards/target), but he only allowed 75 yards on 14 targets (5.4 yards/target) in the other 4 games combined. Those other 4 games look good, but you can’t just ignore that he got destroyed by the best WR he faced.

  • Competing with Shelley for the nickelback spot will be 2nd year man Kindle Vildor and rookie 6th round pick Thomas Graham. Vildor quietly had a decent rookie season when he was pushed into action following Jaylon Johnson’s injury late in the year. If he can make a sophomore improvement, Vildor could solidify the nickelback spot, or even potentially beat out Trufant outside.


Jaylon Johnson

Finally, we come to Jaylon Johnson, who the Bears are counting on to be their top CB this year (and beyond). On the surface his numbers in the table above look awful, but a little more context is needed. Johnson actually started off last year playing incredibly well before getting dinged up. He ultimately had to shut down and miss the last month or so of the season. As you can see in the table below, Johnson’s efficiency plummeted as the season wore on.

In those first 4 games, Johnson was heavily targeted but performed like an elite CB, giving up only 41% completion and 6.5 yards/target (top 30% for all CB). But notice what happens after that: his yards/target mark takes a sharp turn for the worse, and all of a sudden Johnson performed like a bottom 10% CB. I included other advanced statistics to show that Johnson’s style didn’t change yet in this sample: teams were still targeting him fairly deep, and he was not giving up many yards after the catch (YAC). This suggests to me he was still playing tight man coverage; the only big difference between these 1st two samples is that the completion percentage rose. Playing tight coverage and forcing your opponent to complete difficult passes down the field doesn’t work if they actually complete those passes.

Now look at those last 4 games, starting with Chicago’s first game against Minnesota. I separated these out because Johnson missed the end of that game with injuries, which he would continue to try and play through for the next 3 weeks. Look at how those injuries changed his playing style though. His average target depth plummeted to less than half of what it had been, indicating that started targeting him underneath. This was likely because Johnson couldn’t jam receivers at the line of scrimmage due to his injured shoulder, which forced him to back off and make sure he didn’t get beat deep. He then tried to come up and tackle his man after the catch, but was unable to do so effectively due to his injured shoulder, which is why his missed tackles and YAC both skyrocketed.

This really gives 2 concerns with Johnson:

  • His shoulder. The shoulder injury was an issue in college too, and was one of the main reasons he fell to the 2nd round. Johnson says he is 100% healthy now, but will he be able to stay that way?
  • His effectiveness when healthy. Sure, Jaylon’s first four games were great, but he was still healthy for that middle 5 game stretch of the season, when he did not hold up well. Was that a sign of the NFL figuring him out?

If we assume Johnson stays healthy this year (which is a big if given his history), he needs to figure out what happened during that middle stretch of the season so he can avoid being picked on like that again. Johnson is the closest thing to a sure thing the Bears have at cornerback, which is very frightening considering the valid questions surrounding him.


Wrap Up.

It’s not hard to make either an optimistic or pessimistic argument about Chicago’s cornerbacks heading into 2021.

On the optimistic side, Jaylon Johnson and Desmond Trufant have both shown he can play at a high level in the NFL when healthy, and the trio of young defenders (Shelley, Vildor, and Graham) competing at nickelback all have given you reasons to hope they can be capable in the NFL (I didn’t talk about Graham in this article, but he was a productive college CB who fell in the draft because he opted out of the 2020 season).

On the pessimistic side, neither Johnson nor Trufant have shown they can stay healthy. Johnson started to struggle last year even before he got hurt, Trufant is 31 and hasn’t been good since 2018, the trio of young defenders competing at nickelback were all 5th or 6th round picks, and the 2 who have played so far in the NFL have looked average at best.

It’s scary to go into the season with so much uncertainty at such a key position, but if nothing else, 2021 will give the Bears clarity about what they need to do at CB before 2022, which is when their next contention window might open up. Using Justin Fields’ rookie season to figure out exactly what they have with all their young cornerbacks is actually a pretty good big-picture approach, even if it might look ugly on the field at times.

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