It’s one of football’s oldest maxims: the key to winning the game is to win the turnover battle. This works better as an explanation for why a team won rather than as a cause of success — correlation doesn’t equal causation, of course — but that doesn’t mean the stat is useless.
We know that turnover rates have declined significantly over the last several decades. So here’s the question of the day: does winning the turnover battle matter more or less now than it used to?
As it turns out, the importance of winning the turnover battle has been remarkably static throughout NFL history. Last year, teams that won the turnover battle won 78% of their games. And from 2007 to 2016, teams that won the turnover battle won 78% of their games. In the decade of the ’70s, when turnover rates were much higher, teams that won the turnover battle won 78% of their games. From 1950 to 2016, the average winning percentage of teams that won the turnover battle was 78%, too. Take a look: [click to continue…]
On Sunday, I looked at turnover rates for every year in the NFL since the merger. Today, I want to re-examine turnover data but in a different light. In 2014, the average team committed 23.7 turnovers. As you might suspect, there’s a strong relationship between turnovers and winning percentage, with a correlation coefficient of -0.56. This says nothing about causation, of course, and the causal arrow does in fact run in both directions (committed fewer turnovers leads to more wins, and winning in games leads to fewer turnovers).
Here’s another way to think about the relationship between winning percentage and turnovers. The Patriots were responsible for 4.7% of all wins this year and committed 13 turnovers; as a result, when calculating a weighted league average turnover total, I made New England’s 13 turnovers worth 4.7% of that total. Meanwhile, the Buccaneers and their 33 turnovers were only worth 0.8% of the weighted league average turnover total, since Tampa Bay was responsible for just 0.8% of all wins.
Using this methodology, the weighted league average turnover total in the NFL was 22.5 per team, or 95% of the unweighted league average. I used that same methodology to calculate the percentage of “weighted league average turnover total” to “unweighted league average turnover total” for each year since 1960. In the graph below, the blue line represents the NFL ratio, while the red line represents the AFL ratio. [click to continue…]