Patriots fumbles, part 87

No one wants to read about Patriots fumble rates, and I don’t want to write about Patriots fumble rates.

But I can’t not write about this.

The football person behind the initial commotion regarding low fumble rates was interviewed recently for a podcast. In response to a question about the 2015 season, in which the Patriots once again held onto the ball better than the rest of the league, the football person’s response was as follows:

One thing I noticed is that the weather and the climate up there during New England games was abnormally warm, which is one of the reasons that I found it phenomenal and crazy that they were having so few fumbles because as you know, and as I’ve studied and analyzed, it’s much more difficult to hold onto the football when you are playing out in the cold. So it was crazy how well they were able to hold onto the ball. But last year it was pretty warm, they didn’t have many cold weather games, and their fumble rate was pretty good as well.

Two suggestions were made clear:

1 – The weather during Patriots games was abnormally warm.

2 – It’s much more difficult to hold onto the football during cold weather

Let’s check these claims. Data from Armchair Analysis.

1 – The weather during 2015 Patriots games was abnormally warm.

A side-by-side boxplot should do the trick.

Here’s the temperature during Patriots games across the last 16 years.


The median, first quartile, and minimum game-time temperatures during Patriots games were not obviously different last year, and the temperature distribution in 2015 matches most of the prior years.  It certainly does not appear to have been an “abnormally warm” year.

Writer’s claims: 0-for-1.

2 – It’s much more difficult to hold onto the football during cold weather

This is also straightforward to check out.

Using every game since 2000, I linked the game’s temperature to the fumble rate of the participating teams, defined as the total number of offensive team fumbles divided by the number of offensive team plays. So, 2 fumbles in 130 plays would give a fumble rate around 1.5%, or 0.015. If fumbles were associated with low temperatures, we would expect to see a decline in game-level fumble rates with increasing temperature.

Here’s a scatter plot.


While there’s a slight dip around 45 degrees, it’s neither statistically nor practically significant. The smoothed line moving through fumble rate and temperature is nearly perfectly horizontal. On aggregate, the cumulative rate of fumbles is relatively consistent across temperature (Note that a better analysis would probably use temperature in a model with play-level information).

Writer’s claims: 0-for-2.

So what does this mean

The Patriots led the league with one of their lowest ever fumble rates again in 2015, which I have little double links to their style of play and their success (such as red-zone plays, playing with the lead, kneel downs, etc).

Despite the new evidence, our podcast guest appears to still be holding onto the idea that something funny is going on. Moreover, he’s doubling down on false claims, ones which at first glance appear reasonable. Like the initial analysis from a year ago, however, it’s mostly a bunch of hot air.




  1. I wonder whether the Armchair Analyst may have meant Patriots *home* games were abnormally warm. Not that it would change the fact that overall the temp wasn’t a factor last year, but could you rerun that box plot with just home games?

  2. Why, it’s almost like the person who generated this unsupported theory is unwilling to admit he made a mistake! Wouldn’t want his 15 minutes of fame to run out.
    Let’s be clear: this is a theory flawed in many respects
    – there is no evidence that air deflation affects fumble rates
    – there is evidence that fumble rates vary from player to player
    – there is evidence that Beilchick prefers players with low fumble rates
    – and finally, there is no evidence that the Patriots tampered with footballs

    So basically this guy is supporting an unsupported hypothesis with no prior evidence over a theory with ample evidence supporting it. And when a consequence of his theory fails to materialize, he invents a new ad hoc theory in order to justify not simply admitting having made a mistake.

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