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How Much is an Elite Kick Returner Worth?

| February 17th, 2020

Earlier this offseason, I suggested the Bears could release Cordarrelle Patterson to free up just under $5M in cap room. A number of people responded that Patterson was the best kick returner in the NFL in 2019 and thus was worth the money. I wasn’t sold that any kick returner was worth that much, but set out to figure out just how much value they add.

Here’s the general setup:

  • I used the Pro Football Reference Drive Finder to look at every drive over the last 5 years that started with a kickoff and didn’t include any kneeldowns.
  • I split the field into 10 yard ranges.
  • I tallied up touchdowns and field goals from drives that started in each field position range to figure out average points/drive. Note: this assumes all touchdowns net 7 points, which is not technically true, and fails to factor in anything about offensive quality.

Based on that approach, here’s what I found the average points expected for drives off of kickoffs that started in a variety of field positions.



This generally matches expectation, as teams are expected to score more points the closer to the opposing end zone they start. By the time they’re inside the opponent 40 yard line, the expected points are higher than a field goal.

Using this data, I then looked at the Bears’ starting field position off of kickoffs in 2018, when they did not have Cordarrelle Patterson vs. 2019, when they did.


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The Non-Trubisky Offensive Issue: Personnel Usage Remains a Problem

| February 10th, 2020

It’s no secret that I’ve blamed quarterback Mitchell Trubisky for the lion’s share of Chicago’s offensive shortcomings in 2019, while pointing out contributing factors elsewhere: tight end, run blocking, Tarik Cohen…etc. But I truly believe that a competent quarterback would have put the Bears in the playoffs in 2019.

However, it’s important not to get too fixated on one issue and ignore other problems. So today I want to look at offensive issues from 2019 that have absolutely nothing to do with Mitchell Trubisky, but instead are due to what I believe to be poor coaching decisions regarding personnel usage.


Personnel Predictability

How predictable was Chicago’s offense when several of their key players were on or off the field?

The table below shows changes in run percentage when skill position guys who played between 35-65% of the snaps were in the game vs. on the sideline.

  • On the high end, that excludes players who almost never leave the field (Allen Robinson played over 93% of offensive snaps in 2019) because their “off field” splits would be too small to be worth considering.
  • On the low end, it excludes situational players who often only come in for situations where a run or pass is expected (ie the 4th WR in a 4 WR set for 3rd and long, or the 2nd TE in a short-yardage set).

Instead, I want to look at how the Bears deployed their key skill position players as they rotated through in a game.

(Note: This data is pulled from the NFL Game Statistics and Information System, which includes sacks and QB scrambles as passing plays.)

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Least Explosive Team in the NFL, or the Story of the 2019 Chicago Bears

| February 4th, 2020

I’ve been working my way through the Bears’ 2019 performance to see what changed from 2018 that caused them to slip from 12-4 to 8-8. Today, I want to look at explosive plays, which I found last season have a strong correlation to overall offensive performance.

There are a variety of definitions for explosive plays depending on who you ask, so I want to clarify I’m using parameters laid out by ESPN NFL Matchup, which counts any run that gains 15+ yards or pass that gains 20+ yards as explosive. Let’s start with a preliminary look at how the Bears did in 2019 relative to the rest of the NFL. All data is from Pro Football Reference, with explosive play information coming from the Game Play Finder. Pass percentages were calculated including sacks and pass attempts as pass plays.



That’s ugly.

If you want to compare to 2018, the Bears slipped across the board. They had 71 explosive plays in 2018, with explosive rates of 7% overall, 5.3% on runs, and 8.4% on passes. All of those numbers in 2018 were slightly below average, ranging from 18th to 21st in the league, while they are all bottom 2 in 2019.

So what happened to cause such a slump? Like I’ve done when evaluating both the running and passing games, I want to break down what it looks like for individual Bears players and/or position groups from season to season. That information is shown in the table below, with all cells formatted by 2018 / 2019 data. (I’ll note the pass rates are a bit higher for pass catchers than QBs because they are only out of targets and exclude sacks and throwaways.)


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What Changed in the Passing Game: Volume III

| January 24th, 2020

Today I want to look back at two areas of concern I noted for Trubisky last off-season: deep passes and performance against good defenses.


Deep Passes

Last year, I noted that Trubisky was really good at short passes (15 yards or less past the line of scrimmage) and really bad throwing the ball deep. I also found that short passing performance tends to be less variable year over year than deep passing, which gave us a reason to be optimistic about Trubisky heading into 2019.

Let’s see how that theory played out in 2019.

A few thoughts:

  • So much for short stuff being consistent. Trubisky’s completion percentage, yards/attempt, yards/completion, and touchdown rate all plummeted from 2018 to 2019.
  • Some of the completion percentage can be accounted for by drops (as I have previously addressed), but not nearly all of it on the short stuff. Despite throwing shorter passes in the short stuff, Trubisky completed fewer of them. The end result was an extremely inefficient short passing game.

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What Changed in the Passing Game: Volume II

| January 23rd, 2020

Yesterday, it was discovered that the pass blocking and drops by pass catchers went from really good to about average.

The hypothesis, then, is that the quarterback was largely responsible for the Bears having one of the worst passing games – and thus worst offenses – in the NFL. So today I want to look at Mitchell Trubisky’s performance more closely to see what it can tell us.

On the surface, Trubisky certainly was awful in 2019. He completed 63.2% of his passes (18th in the NFL), averaged 6.1 yards/attempt (last), and posted a passer rating of 83.0 (28th). This was a big step back from 2019, when he was near average in all of those marks (66.6% completion, 14th; 7.4 yards/attempt, 18th; 95.4 rating, 16th).

Evaluating a quarterback’s play statistically can be tricky, because his stats depend both on his offensive line’s ability to block for him and his RBs/WRs/TEs’ ability to catch his passes, both of which are outside of his control. That’s why I started by looking at the offensive line and drops, both of which were worse in 2019 than 2018 but not nearly bad enough to explain bottom 5 production from the quarterback.

It’s also worth noting that Chase Daniel’s production barely changed between seasons. In 2018, he completed 70% of his passes, averaged 6.8 yards/attempt, threw 3 TD and 2 INT, and posted a 90.6 passer rating. In 2019, he completed 70% of his passes, averaged 6.8 yards/attempt, threw 3 TD and 2 INT, and posted a 91.6 passer rating. To be fair, it’s a small sample size – he played 2 games and threw around 70 passes each year – but still, this is at least anecdotal evidence to support the notion that the offense as a whole didn’t change all that drastically.


Advanced Stats

With that said, let’s look more closely at Trubisky’s performance to see if we can hone in on what changed, besides worse pocket presence and less running impact, which were touched on in previous articles. This is going to focus on passing. We’ll start by looking at a smattering of advanced statistics, which come from a combination of Next Gen Stats and Pro Football Reference.

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What Changed in the Passing Game: Volume I

| January 22nd, 2020

It stands to reason that if the offense was mainly responsible for the Bears’ 2019 regression, and the running game didn’t change all that much, most of the regression came from the passing game. And a quick look at the stats backs that up. In 2018, the Bears were 9th in completion percentage, 18th in yards/attempt, 14th in passer rating, and 10th in sack percentage. In 2019, those ranks fell to 14th, 32nd, 24th, and 23rd.

So what went wrong in the passing game? Generally, there are 3 components to examine: the pass protection, the pass catchers, and the quarterback. Let’s look at each one by one.


Pass Protection

Evaluating pass protection statistically is difficult, but thankfully advanced statistics to help with this are getting better. A number of them are shown below, with their ranks out of 32 NFL teams in parentheses. Average time to throw is from Next Gen Stats, Average time to pressure and pressure rate is from Pro Football Reference, and Pass Block Win Rate – a measure of how often a QB has a clean pocket for at least 2.5 seconds, is from ESPN Metrics (source for 2018 and 2019).

 

As I tried to make sense of these numbers, it seemed to me that the change in NFL ranks was often greater than the change in the actual value. Sure enough, it seems that pass blocking was slightly better across the league in 2019 than 2018. The median average time to pressure increased from 2.4 to 2.5 seconds, the median pressure rate dropped from 24.1% to 22.6%, and the median pass block win rate increased from 50% to 59%.

Looking just at the Bears’ numbers, they generally got a little worse in pass protection, but their drop in the rankings looks worse than it is because the rest of the NFL got better. The average time to throw didn’t change all that much and the pressure got there a little faster, but the Bears still ranked right around average both in pressure rate and pass block win rate.

If the pass protection didn’t get much worse, how do we account for the massive uptick in sacks? The Bears went from giving up 33 sacks in 2018 (6.1% of dropbacks) to 45 in 2018 (7.2% of dropbacks).

Well, sacks aren’t only due to the pass blocking, they’re a result of the quarterback as well. Lester Wiltfong of Windy City Gridiron breaks down film on every sack and assigns blame to the person or people he deems responsible (he also splits blame if multiple people mess up).

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What Changed in the Rush Game: Volume II

| January 16th, 2020

Yesterday I dove into Chicago’s 2019 ground game to figure out where it all went wrong. There I found that the Bears missed Mitchell Trubisky’s legs, didn’t change how they used their 2 main running backs much, and saw the largest regression on runs outside of the tackles.

Today, I want to look a little more closely at directional running.

Let’s start by looking at yards per carry, which can be seen in the figure below. Bar height is proportional to yards per carry (ypc), numbers in parentheses are NFL rank out of 32 teams, and bars are color coded according to that. Green = top 10, red = bottom 10, yellow = middle 12.



A few thoughts:

  • I don’t think it’s a coincidence that the red all comes on the right side and the Bears had injury issues at right guard and right tackle this year. The yards/carry actually improved behind left tackle and left guard compared to 2018.
  • The numbers look even better up the middle and behind left guard when you look at runs after the Bears swapped Cody Whitehair and James Daniels back to their 2018 spots. After that, the Bears averaged a combined 4.7 yards/carry on runs to those areas.
  • Runs outside the tackles were fairly poor on both sides, which is new since 2018. I think this speaks more to the blocking of WRs and TEs than the offensive line. The Bears got fewer fewer snaps from Trey Burton, Josh Bellamy, Kevin White, and Taylor Gabriel in 2019, and it appears the young players who took those snaps may have struggled in run blocking.

Now I want to look at this from another perspective using success rate, which can generally be thought of as a measure of staying ahead of the chains. A run is considered successful if it:

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What Changed in the Rush Game: Volume I

| January 15th, 2020

Chicago’s rushing attack was woeful in 2019, finishing 27th in the NFL in rushing yards (91 yards/game), 29th in yards per attempt (3.7 yards/carry), and 26th in success rate on rushing attempts (44%). All three marks showed a decrease from 2018, when they were 11th (121 yards/game), 27th (4.1 yards/carry), and 10th (48%) in those three metrics.

This happened despite having fairly decent consistency in personnel. The starting offensive line was the same (when healthy), and the Bears saw only three primary rushers in both seasons. Tarik Cohen and Mitchell Trubisky were 2 of the 3, with the main rusher changing from Jordan Howard in 2018 to David Montgomery in 2019.

Today I want to look at the running game from a variety of angles to try and figure out what changed to account for the dip in production.


Player vs. Player Comparison

Let’s start out by comparing each player from season-to-season. First, I’ll look at the players who accounted for the majority of rushing attempts each year: Jordan Howard and David Montgomery. Their usage and production was remarkably similar in the two seasons, as you can see in the table below.

Similar playing time, similar carries, similar efficiency. The two were basically indistinguishable from each other, at least on the surface. That really makes you question whether it was worth getting rid of Howard and trading up for Montgomery in the 3rd round last year. At least for 2019, the answer is a resounding no.

This post is focused on rushing, but look at those bottom two rows. One of the reasons to swap Howard out for Montgomery was supposed to be that Montgomery can feature more heavily in the passing game, and thus make the offense less predictable and harder to defend. That didn’t happen in 2019. One of Chicago’s big problems in 2018 was that they were too predictable based on personnel (Tarik Cohen = pass, Jordan Howard = run, Anthony Miller = pass, etc.). In 2019, the offense ran the ball 50% of the time when Montgomery was on the field and only 24% of the time when he wasn’t. For Cohen, those numbers were 25% and 52%. That’s too big of a swing in tendencies based on personnel.

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Don’t Blame Defense for Offensive Regression

| January 13th, 2020

Chicago scored only 17.5 points per game in 2018, the 4th worst mark in the NFL. This was a significant drop from 2018, when they were 9th best in the NFL at 26.3 points per game. I’ve seen some people argue that this is mainly due to Chicago’s defense, which scored 5 fewer touchdowns and forced 17 fewer turnovers in 2019. The logic then was that the offense in 2018 was just as bad, but it was overshadowed by a dominant defense that handed them points on a regular basis.

This argument made me curious, so I dug into the numbers to see if it held up.


Non-Offensive Points

The 2018 Bears had 44 points that were scored by their defense and special teams, while the 2019 version had 16*. If you remove those from the season totals, the 2018 offense scored 277 points (23.6 per game) while the 2019 version scored 264 (16.5 per game).

That means Chicago’s offense scored 7.1 points per game more in 2018 than 2019. The total points scored dropped by 8.8 per game, so clearly the bulk of that was from offensive points, not defense/special teams.

*Quick disclaimer: I tallied touchdowns, field goals and safeties, and applied values of 7, 3, and 2, respectively, for each. These numbers might be a little off because not all touchdowns result in exactly 7 points due to missed extra points or going for 2.


Points Off Turnovers

Of course, points directly scored by the defense is only half of the original argument. The 2018 defense also forced far more turnovers, in theory setting the offense up in better field position for more easy points. In order to see what effect this had, I looked at points scored off turnovers for each team using Pro Football Reference’s Drive Finder. The table below shows the data.

Despite forcing far more turnovers, the Bears didn’t actually get many more points from them. Part of this may because of where the turnovers happened; the average starting field position for these drives was the Chicago 42 in 2018 and the opponent 47 in 2019. Accordingly, the Bears got 2.4 points per drive off turnovers in 2018 and 3.3 in 2019. Because of this, offensive scoring following a defensive turnover changed by only 0.7 points per game from 2018 to 2019.

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Big Picture Stats: What Changed from 2018 to 2019?

| January 8th, 2020

The 2018 Chicago Bears went 12-4 and outscored their opponents by 138 points, the 4th best mark in the NFL. Expectations for the team were sky high heading into 2019, but Chicago responded by falling flat. They finished 8-8 and were actually outscored by 18 points over the course of the season.

So what changed from 2018 to cause such significant regression? That’s exactly what I’ll be looking at over the first part of the off-season to see what areas the Bears need to prioritize improving for 2020. Let’s start today with a general overview of all three phases.


Offense

Chicago’s offense was not great in 2018, but it took a decided turn for the worse pretty much across the board in 2019, as you can see in the table below. DVOA is a metric from Football Outsiders intended to be an all-encompassing measure of how well a unit performs. Values in parentheses are NFL rank out of 32 teams.

A few thoughts:

  • The 2018 offense could generally be described as average to slightly below average. The 2019 version was one of the 4-5 worst in the NFL.
  • The run game actually didn’t change all that much, remaining fairly consistently bad in both years. This is probably why the Bears shook up their offensive coaching staff this off-season. I’ll have a more detailed look at what did and did not change in the run game in the next few weeks.
  • The passing offense went from average to possibly the worst in the NFL. Some – but certainly not all – of this can be attributed to a decrease in pass protection, though notice the pressure rate allowed was still average, making pass blocking one of the strongest areas of the offense. I’ll take a much closer look at the passing game in the near future.
  • Pretty much the only area where the Bears actually improved was that they turned the ball over less. This is why their DVOA – which heavily weights turnovers – didn’t fall as far as most of the other statistics suggest it should have.

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