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Possible Regression in 2019: A Mathematical Analysis

| July 22nd, 2019

For the first time in a long time, the Chicago Bears were legitimately fun to watch in 2018. Following years of terrible, boring teams, they went 12-4, scored some big man touchdowns, had plenty of awesome celebrations, and started the most exclusive club in the country to celebrate their wins.

But 2018 was last year, and now I’ve seen some worry that it will prove an aberration. They point to the 2017 Jacksonville Jaguars, who made a similar jump from years of awful to a division win and playoff berth before falling back to Earth in 2018, as a sign of what is to come.

While I’ve been on the record going back to 2017 that this is the earliest year when their title window will fully open, I still wanted to take a realistic look and see if there might be reasons to expect regression in 2019 instead. Accordingly, I’m looking at recent NFL history to see how teams similar to the 2018 Bears followed it up the year after. Since the NFL switched to its current 32 team, 8 division format in 2002, that serves as a nice starting point for this study. I looked at wins per year for all teams from then to 2017 (the last year in which we can track how teams did the year after), and identified teams similar to the Bears in a variety of ways. Full data can be seen here.


12+ Wins

To start out, I looked at teams that won 12 or more games in a season, as Chicago did in 2018. That data can be briefly highlighted like so:

  • Teams with 12+ wins: 74
  • Average # wins: 12.7
  • Average # wins next year: 9.6
  • Net change: -3.1 wins

The average team that won 12+ games decreased by just over 3 wins the following year, which makes a lot of sense. It’s hard to win 12 games in a season, which is why fewer than 5 teams per year, on average, do it. Remaining one of those top 5 or so teams for a 2nd year straight is no small feat.

Of course, it’s important to remember that the average decrease of 3.1 wins sees a large distribution in how it plays out for individual teams. The range went from 4 more to 10 fewer wins! Roughly 1/4 of the teams (16) won just as many or more games the year after, about 1/3 (23) won 12+ games again, and over half (38) won 10 or more the next year, which means they likely stayed in the playoffs.

Looking at it from this perspective, it seems likely that the Bears will win fewer games in 2019 than they did in 2018, but that doesn’t mean all hope is lost. The slight majority of teams from this sample remain playoff caliber.


Big Jump

Now let’s look at things from a slightly different perspective, focusing on the jump teams took to reach a playoff-caliber season. For this sample, I looked for teams that went from losing 10+ games (winning 6 or fewer) to winning 10+ games, and then tracked how they did in the season after.

  • Teams in sample: 35
  • Average # wins: 10.7
  • Average # wins next year: 7.3
  • Net change: -3.4

Once again we see that teams decrease by just over 3 wins in the following season. But once again, we see a large range in individual team outcomes, from an improvement of 2 games to a decrease of 9. Only about 1/4 (9) won 10+ games again the following year.

Of course, I’m struck by the somewhat low average number of wins here, at least relative to the sample size above. In my opinion, it’s a lot easier to luck your way into 10 wins than it is 12. The higher you go, the less margin there is for error, and the more skill as opposed to luck is required to win enough games.

Looking at the 35 teams in this sample set, only 4 of them won 12+ games in their jump year. Those 4 all won 9 or more games the year after the jump, with an average of 10.1 wins. That is admittedly a small sample size, but I think it matters that the teams at the top of that list all showed it wasn’t a fluke by staying as at least borderline playoff teams the year after.


New Coach and/or QB

Finally, I wanted to look at a subset of the 35 team sample above to see what teams were most similar to Chicago in terms of having a new head coach and young QB entering his 1st or 2nd NFL season. Both of those factors matter so much in terms of the product on the field, so it is a reasonable hypothesis that improvement in those positions might lead a to a jump that is more sustainable.

Again we find a very small sample size, but the results are encouraging. There are 4 teams that fit the bill: the 2008 Atlanta Falcons, 2012 Indianapolis Colts, 2013 Philadelphia Eagles, and 2017 Los Angeles Rams. These four averaged 10.8 wins in the first year of the QB/coach combo, and followed that up by maintaining a 10.8 win average in the 2nd year. All four teams won at least 9 games in year 2, again indicating that they were fringe playoff teams at worst.


The Wrap-Up

Winning 12 games in the NFL is hard, so just from that perspective it’s likely that the Bears will win fewer games in 2019 than they did in 2018. But that doesn’t mean they’re not going to be good. They match the profile of recent teams who remain in consistent playoff contention for a couple of years more than that of a team that has one good year before fading back into obscurity.

So stop comparing the Bears to the 2017 Jaguars, and look instead to the 2017 Rams. They made a jump to the playoffs behind a hot new offensive coach who got much improved play out of a 2nd year QB that had a rough rookie season. They then lost their home playoff opener.

That sounds familiar, right?

They followed it up by being even better in 2018 and winning two playoff games en route to a Super Bowl loss. Let’s hope the Bears can follow that track, only one-up the Rams by actually finishing the job.

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