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Will the Bears Defense Regress in 2019? History Tells Us…Not So Much.

| July 15th, 2019

Chicago’s defense was really, really good in 2018. They led the NFL in points allowed, turnovers forced, touchdowns scored, and passer rating against, and finished 3rd in both yards and sacks. They finished as the runaway best defense in Football Outsiders’ DVOA, which is intended to be an all-encompassing metric, and even finished as the 8th best defense ever in DVOA’s database, which runs back to 1986.

Now as we head into 2019, fans are rightly wondering if Chicago’s defense can repeat that performance. While I won’t pretend to be able to predict the future, I can look at the past to see what it might have to tell us. So I looked at top defenses in recent NFL history and measured, through a variety of metrics, where the 2018 Bears excelled. Then I looked to see how they followed that up in the next season. Full data collected can be viewed here for transparency’s sake.


DVOA

The DVOA system is set up such that an average defense gets a score of 0, with negative numbers indicating you are better than average (the farther from 0 the better). The Bears finished with a final score of -26.0, so I looked at other teams in the last decade (2008-17) who finished at -20 or better. This was quite a small list, as it featured only 10 teams. Here’s how they fared in the season following that dominant performance:

  • Average DVOA: -25.1%
  • Average following DVOA: -8.8% (8th in NFL)
  • Change: 16.4%
  • # teams with better DVOA following year: 0
  • # teams top 5 in DVOA following year: 5
  • # teams top 10 in DVOA following year: 8
  • # teams below average in DVOA following year: 1

First, notice that none of these defenses were as good the following year. This isn’t surprising; there were only 10 teams in 10 years who achieved this caliber of DVOA. The odds of doing that twice in a row are very low.

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The Most Complete, Data-Driven Breakdown of the 2018 Bears Pass Defense Available

| July 8th, 2019

The Bears had the best pass defense in the NFL last season, finishing 7th in yards, 1st in yards/attempt, 1st in interceptions, and 1st in passer rating against. Now I want to look at the performance of each individual player in coverage, using stats from The Quant Edge.

Where They Lined Up

Let’s start by taking a look at where the CBs lined up. I’m only looking at the CBs here because all of the LB are listed as “LB” and all of the safeties “FS” for pretty much the whole time, thus those designations aren’t particularly helpful.



 

Pretty much the only point I wanted to make here is that the Bears played their CBs in specific spots, not against specific match-ups. Kyle Fuller covered the left (right side from offense’s perspective), Prince Amukamara the right, and Bryce Callahan the slot. Toliver filled in for Prince when he was out hurt (and some for Fuller late in blowouts), and McManis for Callahan.

Of course, Callahan is now gone, so it’s worth noting that 89% of Buster Skrine’s snaps came in the slot in 2018. It’s reasonable to think that will be his role in Chicago as well, but he has played outside a good bit in the past, so maybe he moves if Fuller or Amukamara get hurt and the Bears like McManis or Duke Shelley at nickelback.

It’s also fair to wonder if new defensive coordinator Chuck Pagano will ask his cornerbacks to move around a little bit more. When he was the head coach in Indianapolis in 2017, no cornerback played more than about 90% of their snaps in one spot. That’s still mostly intact, but not the 98%/99% Fuller and Amukamara had.

Coverage Statistics

Now let’s look at how well each player did in coverage. The table below shows that data for every CB, S, and ILB who played a meaningful role in 2018 (OLB are excluded because they saw very few targets due to rushing the passer more than dropping into coverage. Yes, even Leonard Floyd). Positions are color coded to make tracking the table easier.


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A Player-By-Player Examination of Chicago’s 2018 Defense

| July 1st, 2019

As a unit, the Bears defense finished 3rd in the NFL in yards, 1st in points, and 1st in turnovers. Now I want to look at the impact each individual player had on the defense, as much as is possible. To do so, I’m using stats from The Quant Edge.


Defensive Line

Let’s start on the defensive line, where we can get a look at how often each player was on the field and how successful the defense was when they were in or out of the game. This can be measured through yards per carry (YPC), yards per pass attempt (YPA), and success rate, which is generally a measure of how effectively offenses stay ahead of the chains. Higher success rate

The table below shows data for defensive linemen who both played and missed 100 or more snaps, and is set up such that numbers for each category are in game/out of game for an easy comparison. Notable differences are highlighted in green (good) or red (bad).



A few thoughts:

  • First, note that this data does not necessarily mean a player was good or bad, especially when we get to the smaller sample sizes (in terms of snaps played or snaps missed). But it can be really useful for players in the middle, who both played a lot of snaps and rotated out for plenty as well.
  • Speaking of those players, hello Eddie Goldman and Akiem Hicks! Look at those splits against the run. Those two make up a formidable duo up front for the Bears, and allow them to be stout against the run even in nickel looks when they only have two defensive linemen on the field. If you’re looking for more specifics here, Jack Soble of The Loop Sports did a great film breakdown of Goldman’s impact on the run game.
  • Roy Robertson-Harris had some flash plays this year, but the data suggests he didn’t really have a positive impact on the defense as a whole. That’s plenty understandable in the run game, because he’s not really a typical 3-4 defensive lineman and doesn’t 2-gap as well as the rest of these players.
  • Sometimes the differences between yards/play and success rate can be confusing. Let’s look at Jonathan Bullard as an example. In the run game, teams averaged a lower yards/carry when he was on the field, which is good, but had a higher success rate, which is bad. That tells us that the Bears gave up fewer long runs, but still let teams stay with or ahead of the chains a bit more when he played. That could mean he played in a lot of short-yardage situations, where a 1-2 yard run is a success but keeps the average gain low. On the flip side, teams averaged more yards/pass when he was on the field, but had a lower success rate. That means the Bears didn’t give up completions as much, but gave up more big plays.

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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.

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Projecting Cody Whitehair’s Coming Extension

| June 19th, 2019

Offensive lineman Cody Whitehair has quickly become a stalwart on Chicago’s offensive line. In three years with the Bears, he has been a high-quality center who missed only 26 total offensive snaps, and he was rewarded with his first Pro Bowl appearance in 2018.

Now that he has three seasons under his belt, Whitehair is eligible for a contract extension, and friend of Da Blog Adam Jahns reported earlier this offseason that this is expected to happen before the 2019 season begins. So today I want to take a look at contracts signed by comparable players over the last few years to see roughly what Whitehair’s contract should be expected to look like.

This is a bit more complicated than usual because of Whitehair’s position change this offseason; after three years as the starting center, he is shifting to left guard. This is actually a good move for Whitehair, because guards actually make a little bit more money than centers do. So I imagine in negotiations the Bears will try to pay Whitehair as a center, which is what he played to earn this contract, while Whitehair’s camp will push for him to be paid as a top guard, which is what the Bears expect him to be going forward. Thus we’ll look at contract comparisons for both positions to see how much they differ.


Center

The table below shows recent contract extensions signed by centers after 3 years in the NFL. I am not looking at free agent deals, because those are usually higher. Signing after three years – with one year left on the rookie deal – is usually the best time for a team to get terms that are slightly more friendly. All numbers used in this piece will be from Spotrac.

Some factors to consider:

  • All of these players signed at a younger age than Cody Whitehair, who will be 27 in the 2019 NFL season. That shouldn’t be a huge deal, but is probably a consideration when thinking about length. I’d guess Whitehair’s contract falls in the 4-5 year range.
  • The closest comparison to Whitehair in terms of player quality here is probably Travis Frederick, as he’s the only one of this bunch with a Pro Bowl to his name.
  • Looking at when a deal was signed is important because the salary cap keeps going up. It was $155 million in 2016, $167 million in 2017, and will be $188 million for 2019. Thus expect contracts to be inflated appropriately.

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In Appreciation of Tarik Cohen

| June 17th, 2019

Tarik Cohen followed up a solid rookie campaign with a really good sophomore season in 2018. Despite playing less than half of the available offensive snaps and getting fewer than 100 carries and 200 total touches, he finished with 1,169 yards from scrimmage, scored 8 touchdowns, and was one of the most explosive players in the NFL. For good measure, he was also a 1st team All Pro as a punt returner after leading the NFL in punt return yards and finishing 5th in yards per return.

Despite all of this, I think Cohen’s limited snaps and touches keep people from appreciating just how valuable he is to the offense. Cohen’s diminutive stature keeps him from being a conventional lead running back, but he still has a substantial impact on offensive production.

And there are actual numbers to back it up. The graph below shows the relationship between the total number of touches (carries or pass targets) that Cohen gets and how many points the offense scores. In order to account for different numbers of snaps in games, I looked at Cohen touches out of total snaps for that game. So if he got 10 carries + targets and the offense played 20 snaps, 50% of the plays went to Cohen.



There’s a pretty clear trend where the offense scores more points when more plays run through Cohen. We see that anecdotally as well, as the Bears scored 27 or more offensive points all 5 times Cohen was involved in 14+ plays in a game, and only 1 time in the other 12 games (including playoffs). An R2 value of 0.65 gives a strong number to support this correlation (a value of 0 would mean there is no relationship, while 1 would mean the relationship is perfectly linear).

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Mitch Trubisky, Do We Have a Problem? (No. Not yet.)

| June 10th, 2019

I’ve been doing a deep dive into Chicago’s offense from a variety of perspectives, and want to wrap that up today with a closer look at Trubisky. I’ve already written about him several times this offseason, talking about:

Today I want to look at how wildly his performance fluctuated with the caliber of defense that he faced. Honestly, this was not the article I set out intending to write. I first did this research with the hypothesis that Trubisky did better in early games – when there was less pressure from a national audience – and struggled in primetime games where more people were paying attention. Just watching those games, it always looked to me like Trubisky was tense, like he was putting too much pressure on himself and thus not performing well. It seemed to me like he was more relaxed in early games that got less attention, which enabled him to just go out and play.

And there might be some truth to that; Trubisky posted a passer rating of 114.4 in early games, 89.9 in late afternoon games, and 63.0 in night games. But two of the four night games (Green Bay and Seattle) came in the first two weeks of the season, when Trubisky was just not comfortable in the offense yet. He was awful in an afternoon game against Arizona the next week too before breaking out in Week 4.

I then noticed that the other two night games – when he also struggled mightily – were against the Rams and Vikings, two of the better defenses the Bears faced all season. In fact, those were statistically his 2 worst games of the year, with 3 of the next 4 bad ones being the 3 weeks before he broke out. And thus a different hypothesis emerged, and I started exploring how well Trubisky performed against good and bad defenses.

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A Complete Breakdown of the Quarterback Position’s Efficiency for 2018

| June 3rd, 2019

The offseason is the perfect time to do a deep dive into what exactly we saw on the field last year, so today I want to look more closely at how Chicago’s QBs performed in 2018. To do so, I’m going to compile all of the information about individual targets from The Quant Edge and use it to see what we can learn about QB play as a whole.

Before we begin, I want to note two limitations.

  • This doesn’t split data into individual QBs, so unfortunately I can’t separate out the games Trubisky played and use only those. Still, Trubisky accounted for 85% of Chicago’s pass attempts in 2018, so this should still be useful to help us generally learn more about him.
  • This data only includes WRs and TEs, so I will not be able to incorporate any information about the 132 pass attempts that went to RBs (and Bradley Sowell). I really wish they included Tarik Cohen in particular, considering he finished 3rd on the Bears in targets, but no such luck.

With that said, let’s get started.


Route Efficiency

How effective were Chicago’s QBs targeting various routes?

That data can be seen in the table below, sorted from most to least targeted. I also highlighted routes that were particularly efficient in green, and routes that were particularly inefficient in red.

A few thoughts:

  • The Bears loved their go routes, but they sure didn’t work well in 2018. As previously noted, Trubisky had issues with deep accuracy, and maybe that was part of the problem. And you can argue there is value in go routes to back the defense off. But still, 26% completion rate is not acceptable for a route they utilize that frequently, and there were 5 interceptions thrown on go routes as well. If you’re looking for one bright spot on go routes, Allen Robinson caught 40% of his targets for over 16 yards/target.

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How Did the Bears Use Their Receivers & Tight Ends in 2018?

| May 28th, 2019

The offseason is the perfect time to do a deep dive into what exactly we saw on the field last year, so today I want to look more closely at how Chicago used their WRs and TEs in 2018.

Where They Lined Up

Let’s start by looking at where these players lined up, which can illustrate just how versatile they were (or were not). All data comes from The Quant Edge except for Tarik Cohen’s, which is from Pro Football Focus.



A few thoughts:

  • The Bears generally moved their main weapons all over the place. Allen Robinson, Taylor Gabriel, Trey Burton and Tarik Cohen – who spent about 1/3 of his snaps out of the backfield – were all extremely versatile.
  • We also see that versatility in some of the depth pieces, most notably TEs Adam Shaheen and Ben Brauneker and WR Josh Bellamy. Dion Sims, on the other hand, was pretty much always an in-line TE.
  • The other piece who didn’t move much was Anthony Miller, spending the vast majority of his time in the slot. This is because he played almost exclusively at 3rd WR alongside Allen Robinson and Taylor Gabriel. His versatility was demonstrated in different ways, as we’ll see below, and I think he’ll get moved around a lot more next year after usurping Gabriel as the WR2.

How They Were Used

Now I want to look at what routes the main options – Robinson, Gabriel, Burton, and Miller – got their targets on. The table below has the percentage of targets each player received on various routes, with the routes arranged by descending order of total targets. Numbers that are low compared to peers are highlighted in red, while numbers that are high are highlighted in green. All data from The Quant Edge.

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Examining 2018 Offensive Trends

| May 20th, 2019

The offseason is the perfect time to do a deep dive into what exactly we saw on the field last year, so today I want to look more closely at how frequently and effectively the offense used various formations and personnel groupings in 2018. We’ll look at it from a few different perspectives.

Shotgun vs. Under Center

(These stats all come from NFL Savant unless otherwise noted.)

The Bears operated mainly out of the shotgun in 2018, with just over 80% of their snaps (832 out of 1034) coming there. As I noted at the bye, this is in line with the Andy Reid offense that Matt Nagy brought over from Kansas City. Reid’s Chiefs teams have been 70-75% out of the shotgun in the last few years.

The table below shows how frequently and efficiently the Bears ran it out of shotgun vs. under center.



A few thoughts:

  • That looks a bit imbalanced to me, but is actually a better run/pass balance out of shotgun than any Reid team has shown in Kansas City.
  • I’m tempted to say the Bears should avoid going under center, but the low averages there are probably due to them mostly being in short yardage situations, when plays are designed to get 2-3 yards and a first down/touchdown. Success rates would be a good way to confirm if that is indeed the case, but unfortunately that information is not available with this kind of split.
  • The yards/carry split happened with both main running backs, according to Player Profiler. Jordan Howard saw 138 carries out of the shotgun and averaged 4.2 yards/carry, and averaged 3.1 yards/carry on his 112 carries from under center. Tarik Cohen averaged 4.7 yards/carry on 81 shotgun runs and 4.1 yards/carry on 18 runs from under center. New Bear Mike Davis saw 75% of his runs from shotgun last year and averaged 4.6 yards/carry, so there is reason to hope he will thrive in these runs as well.

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