How Regression Is Affecting 2019 NFL Win Totals
Jonathan Dyer-USA TODAY Sports. Pictured: Alvin Kamara and Mark Ingram
- In 2018, the Saints, Rams, Chiefs, Bears and Chargers won 12 or more games.
- Since 2003, there have been 70 teams that won 12 or more games, and on average they won 9.6 games the next season.
In 2018, five NFL teams won 12 or more games: The Saints, Rams, Chiefs, Bears and Chargers.
Oddsmakers expect each franchise to take a step back in 2019.
On average, the best teams from last season are expected to win 2.3 fewer games this fall according to the posted win totals. Why are bookmakers predicting a worse record for these 2018 playoff teams?
Answer: Regression. NFL teams that finish one year with a winning record tend to revert to the mean, which is an 8-8 record. This is true for losing teams as well.
Using Bet Labs, we pulled every team’s record from 2003 to 2018. Based on this data, here is what history can tell us about each NFL team’s chances of improving or declining in 2019 based on last year’s record:
Since 2003, there have been 70 teams that won 12 or more games. Only six of these franchises improved their record the following year and on average they won 9.6 games, hence why oddsmakers expect the Saints, Rams, Chiefs, Bears and Chargers to regress this year.
For as much success as those teams had a last season ago, the Jets, Raiders, 49ers and Cardinals were equally as bad winning four or fewer games.
Since 2003, 75 teams have finished a season losing 12 or more games. The next year those same squads on average celebrated 6.8 victories.
That’s not to say it wouldn’t be surprising if the Chiefs, with a 23-year old MVP in Patrick Mahomes, won 12 or more games in 2019, just as they did a year ago. Or if the Cardinals, after drafting another top 10 quarterback and switching head coaches for a second consecutive offseason, struggle to win more than four games.
But regardless of which end of the spectrum on which they fall, NFL teams tend to regress toward 8-8 from one season to the next. The oddsmakers understand this tendency and will set lower win totals for the previous season’s best teams and higher win totals for the worst squads.
So while repeat performances wouldn’t be a shock, they shouldn’t be expected. Look for the best teams in 2018 to decline and the league’s worst to improve.