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Fun with Numbers: Looking at some key Bears statistics

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A turnover differential deep dive, some team defense numbers, and quick hits on Trubisky, Mack, and Cohen

Detroit Lions v Chicago Bears
Not only is 38 the number of Adrian Amos, it’s also the Bears impressive toxic differential total through 12 games
Photo by Jonathan Daniel/Getty Images

Third Quarter Statistics Review

As the Bears finished up the third quarter of the 2018 season with a disappointing loss to the New York Giants, there are a few statistics that are still very promising for this team moving forward. As we did earlier this year, we’ll take a look at a couple of the more important team statistics and hit up some interesting individual numbers.

Turnover Differential

I’m going to spend some time on this one and I’m going to do a little math so buckle in for the ride. Remember that turnover differential is the number of takeaways your defense creates minus the number of turnovers your offense commits. A positive number is good, negative number is bad. I put together a dataset for the 2006-2017 seasons (all readily available data) for turnover differential for the entire league.

My first step was to add up the number of teams over the 12 year period that finished the year with each distinct turnover differential. The worst turnover differential was last year’s Cleveland Browns at negative 28, not particularly surprising for a team that failed to win a game. The best seasons are owned by the 2010 Patriots and 2011 49ers at +28. I then plotted these results on a simple scatter plot below.

A quick guide to reading this chart – there were 20 teams in the 12 year period that finished the year with a turnover differential of zero, indicated by the blue diamond at the 0, 20 intersection. Each blue diamond indicates the number of teams that recorded a season with that final turnover differential. As we move further away from zero in either direction, the number of teams finishing with that specific turnover differential decreases in a very predictable statistical manner. The basic shape (that kind of looks like a mountain) indicated by the solid line shows us a pretty standard normal curve or “bell curve” that you may remember from math class. So far, this was exactly what I expected to see.

I then calculated the standard deviation. I know, more math, but stick with me. The standard deviation allows us to read the chart above to make a little better sense of the data and averages. The standard deviation for this dataset clocked in at 9.5, meaning that any team that finished with a turnover differential of +10 or better was at least one standard deviation above the average (top ~15% of the league) and worth looking at a little closer. Why would I want to do that? The Bears currently lead the league with a +12 in turnover differential.

I then pulled out just the seasons of +10 turnover differential or greater and married this with the number of regular season wins that team earned over the course of the regular season. Of the 384 seasons in the dataset, only 55 had a turnover differential of +10 or better (14.3%). Of those 55 team seasons, 46 made the playoffs, 11 made the Super Bowl, and 6 won the championship game. Again, the chart below is a scatter plot with turnover differential increasing left to right, and regular season wins increasing bottom to top.

There’s really only 1 outlier – the 2013 Tampa Bay Buccaneers. That was the Mike Glennon season and while they lost some close games, they are a bit of a surprise to see on here. Otherwise, some pretty good company on this list. Of the 8 other teams that failed to make the playoffs, 5 teams recorded 9 wins while 2 teams recorded 8. The final team, the 2012 Chicago Bears, won 10 games but missed the playoffs due to some tie breakers and started a 5-year nightmare of fandom. We might consider this an outlier the other way as a turnover differential of +20 likely should have netted the Bears about 12 wins. The 2018 Bears appear poised to finish somewhere in the chart above with a chance to finish with some very good teams. While there are plenty of successful playoff teams that haven’t been very good in this stat, the ball hawking nature of this defense is the reason this team is in the position it currently enjoys and appears to be a winning signature for these Bears.

If we look at the other teams clustered around the Bears at the top of this category for 2018, we find the Rams (+11) and Seahawks (+11) one below and the Saints in the hunt with a +9. With the exception of the Rams, the Bears remaining opponents may offer a course to increasing that number as the Packers (0) and Vikings (+1) are around the league average while the 49ers (-20) are ranked 32nd. This year has been dominated by offensive story lines like the Chiefs and Saints, but stealing possessions and scoring with your defense while taking care of the ball on the other side never goes out of style.

Toxic Differential

Toxic Differential takes the turnover differential and adds in explosive play statistics. An explosive play varies by the site, but the toxic differential numbers that I track are runs of 10 or more yards and passing plays of 25 or greater. The Bears have been particularly good at limited explosive plays as a defense, ranking at or near the top all season. One of the impressive things to note is that the Bears didn’t lose the turnover differential in an individual game until last week against the Giants and have only lost the explosive plays differential once to the Dolphins in week 6.

This is a great season-long stat to track, but it’s also useful to think about during a game. Keeping a mental tally can help you get a sense of where the game is going.

Defensive DVOA

Football Outsiders does an incredible job with their DVOA statistics as they are able to compare defenses across the league adjusting for opponents. It’s a much better way to compare defenses than, say, just looking at scoring or total yards. The Bears have been darlings of this statistic all season, are heavy favorites to finish the year as the top defense, and are closing in on competing with the top rated teams of the past few years too. It’s worth keeping an eye on this as the Bears get closer to securing a playoff berth because that may be the element that, from a competitive standpoint, is able to break through some of these outstanding offenses. The teams of the recent past that have won Super Bowls led with a dominant defense - the Broncos and Seahawks - are teams that show up similarly to these 2018 Bears. Currently, the Bears own the top rated rush defense and the top rated pass defense. The last team to do that? The 2012 Bears.

Briefly on Khalil Mack, Mitchell Trubisky, and Tarik Cohen

Unfortunately, injuries have robbed us of a full season of Mack and Trubisky. Mack’s injury against the Dolphins rendered him fairly useless for that game and the Patriots contest before missing two weeks to fully heal. Mack’s numbers are impressive – 9 sacks, 7 tackles for loss, 5 forced fumbles, and a pick 6. What he’s done to open up the defense is obviously more impressive and shows up as that defensive DVOA ranking and the amazing toxic differential numbers. I don’t think Mack will win the Defensive Player of the Year Award with Aaron Donald wrecking opponents for the high flying Rams, but he’s in great shape to earn a 1st Team All-Pro honor. The numbers he’s putting up and awards and honors he will receive will continue to build his Hall of Fame resume. For a franchise blessed with the best linebacker history in the NFL, this next chapter is going to be fun.

As for Trubisky, the 2 games missed means that Erik Kramer is likely going to retain his single season passing records for one more season. What seemed like a foregone conclusion a month ago is now going to take an amazing December. I’m not going to doubt that Trubisky can do it, but he’ll need to average 343 yards per game to close out the year. It’s worth throwing my tracker out one more time to see where he was at in chasing the team record.

Finally, I had been curious to start the season just how Tarik Cohen would fit into the new offense and whether or not some of the Darren Sproles comparisons would start to take shape or not. Taking a look at the numbers that are, admittedly, buoyed by his amazing individual performance against the Giants, Cohen looks to be on pace to post some impressive numbers. Before the season started, way back in June, I got into a little Twitter tiff with someone who said there was no way Cohen would get to 60 catches, let alone the 70-75 I was hoping to see him get. Sitting at 59 with 4 games to go, I feel pretty good about my prediction.

I’m hard pressed to see why Cohen can’t be compared to Sproles and in fact, he’s been more effective at this point in his career. Sproles’ best season came in 2011, his first with Drew Brees where he caught 86 balls for 710 yards. Cohen may not get close to the 86 mark, but he already has 59 grabs and 659 yards for 4 scores. Let’s say Tarik finishes with something like 75-850 receiving, he has a chance to lead the team in those categories. He’s proven to be a good runner as a 100 carry-per-year guy and he adds juice in the return game. He’s a fun and valuable piece of the future of this offense and yet another great pick by the Ryan Pace regime.

What numbers jump out to you as we enter the final quarter of the season? Hit the comments below or find me on Twitter @gridironborn