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Take heart, Browns fans: there was a 50% chance Cleveland would recover this

Take heart, Browns fans: there was a 50% chance Cleveland would recover this fumble.

There are few statistics more random in all of sports than fumble recoveries. When a football is on the ground, it’s not the case that better teams are more likely to fall on the ball than bad teams: in the NFL, recovering fumbles is nearly all luck and little skill. This is a fact widely accepted by all statisticians, but I figured I would still crunch the numbers just to confirm.

I looked at all teams from 1990 to 2012. First, I looked at fumble recovery rates for teams on their own fumbles. The correlation coefficient between fumble recovery rate in Year N and fumble recovery rate in Year N+1 was 0.00. In other words, there is simply no correlation between fumble recovery rates from year to year. Nada. Zilch. (Of course, fumble recovery rates do vary by type, but that appears to be muted when analyzing fumbles in the aggregate.)

I then looked at fumble recovery rates for teams on their opponent’s fumbles. The correlation coefficient there from year-to-year was -0.02. In other words, there is simply no correlation between recovering your opponent’s fumbles in one year and the next. The best way to predict each team’s fumble recovery rate is to simply project teams to recover about half of all their fumbles.1 If words like regression cause your eyes to roll over, consider this: from 1990 to 2012, the top 20 teams in fumble recovery rate recovered 75.4% of their own fumbles; the following year, they recovered 50.4% of their own fumbles.

With that disclaimer out of the way, who were the best and worst teams at recovering fumbles in 2013? Let me walk through the Cowboys as an example. Last year, Dallas fumbled on offense 18 times, and lost 8 of them. Based on the league-wide average 47.6% recovery rate last year, the Cowboys lost 0.6 fewer fumbles than expected (a negative number here means the team did not lose as many fumbles as they “should” have). Cowboys opponents fumbled 16 times and lost 13 of them; as a result, Dallas recovered 5.4 more fumbles than we would have expected. Overall, this means the Cowboys recovered 6.0 more fumbles than expected, the highest number from last season; overall, on the 31 fumbles in Cowboys games, Dallas recovered 67.6% of them.

Rk
Team
Fum
Fum Lost
FL vs. Exp
Opp Fum
Opp Fum Lost
FR vs. Exp
Total FR vs. Exp3
Fum Rec%
1DAL188-0.616135.4667.6%
2KAN2110022154.54.560.5%
3NWE249-2.4211224.560%
4TEN279-3.924120.64.558.8%
5CIN20100.516113.42.958.3%
6GNB199018112.42.556.8%
7OAK2711-1.926130.62.554.7%
8IND144-2.72612-0.42.255%
9ARI229-1.520100.5254.8%
10STL20100.527152.11.653.2%
11CAR1260.317101.91.655.2%
12SFO20100.5211221.553.7%
13TAM1890.418101.4152.8%
14SEA2610-2.42611-1.4151.9%
15WAS30150.7191010.351%
16BUF3212-3.2217-30.350.9%
17MIA167-0.6146-0.7050%
18CLE1790.91370.8-0.150%
19JAX186-2.62710-2.9-0.448.9%
20ATL17112.918112.4-0.548.6%
21BAL156-1.1218-2-0.947.2%
22NOR1271.3157-0.1-1.544.4%
23HOU219-1154-3.1-2.144.4%
24MIN23132.1178-0.1-2.145%
25PIT16102.421100-2.443.2%
26NYG26152.625120.1-2.545.1%
27PHI191012912-1.8-2.943.8%
28CHI21100259-2.9-2.943.5%
29DET28151.7197-2-3.642.6%
30SDG14103.3156-1.1-4.534.5%
31DEN27163.1259-2.9-638.5%
32NYJ157-0.1182-6.6-6.530.3%
Average20.59.8020.59.80050%

As further proof of the randomness of fumble recoveries, I give you the 2012 fumble recovery rates.2 That year, Washington had the best fumble recovery rate in the league, recovering 70% of all fumbles and picking up an extra 8.4 more fumbles than expected. Then last year, that dropped to 51% and 0.3 more fumble recoveries than expected (and while the 7-win decrease was not due to losing more fumbles, Washington was certainly the beneficiary of good fortune in getting to 10 wins two seasons ago). Atlanta and Houston ranked 2nd and 3rd in fumble recovery rate in 2012, but both were below average last year (well, we’ve now crossed off the 2013 disaster teams). Meanwhile, the Bills, Lions, and Chiefs had the three worst fumble recovery rates in 2012, but collectively recovered 51% of all fumbles in 2013.

In other words, we should expect all teams to heavily regress to the mean when it comes to fumble recovery rate. This is good news for the Jets and bad news for the Cowboys.

In December, I wrote that the 7-6 Cowboys curiously ranked 32nd in yardage differential (Dallas ended the year 31st in that category). In that post, I noted that the Cowboys had recovered 80% of all opponent fumbles, and Dallas also recovered the lone fumble they forced in the final three games of the year. The amazing fumble recovery rate of the Dallas defense is the reason the team ranked as the best at recovering fumbles in 2013, as the offense was just slightly above-average at recovering its own fumbles.

That leads to a very scary conclusion for 2014: last year’s Cowboys defense was actually the beneficiary of some good fortune! Lest you forget, the 2013 Dallas defense ranked in the bottom five of the NFL in passing yards, total yards, net yards per attempt, passing touchdowns, and yards per carry. It’s difficult to comprehend the potential for disaster for the 2014 defense, then, especially after losing DeMarcus Ware and Jason Hatcher and (presumably) regressing to the mean in fumble recovery data. Dallas ranked “only” 26th in points allowed, in part because of that great fumble recovery rate, so, uh, get ready for Tony Romo to get blamed for a lot of 34-31 losses this year?

The Cowboys defense (and special teams) forced 16 fumbles and recovered 13 of them. On the other end of the spectrum, the Jets defense (and special teams) forced 18 fumbles and recovered… two of them. In fact, the 2013 Jets were the first team in NFL history to recover fewer than three opponent fumbles. In 2012, the Jets recovered 12 of 16 forced fumbles; we should probably expect the 2014 team to recover about 8 or 9 opponent fumbles, which should help offset the regression to the mean that would otherwise be projected by the team’s Pythagenpat record.

One other team stands out with an extreme fumble recovery rate from 2013: the AFC Champion Broncos. Last year, Denver recovered six fewer fumbles than we would expect based on league-average data. Interestingly enough, for the second year in a row, the Broncos recovered about 3 fewer of their own fumbles and 3 fewer of their opponent fumbles. But keep in mind that we would expect one team to have bad luck two years in a row. It appears Denver is that team, but that doesn’t mean we should project this “trend” to continue in 2014.

  1. Actually, the best number is usually just shy of fifty percent. []
  2. Note that there, the “FL vs. Exp” column is negative for losing a lot of fumbles. I made the stylistic decision to reverse that this time around. []
{ 21 comments }
  • curt durt March 27, 2014, 2:41 pm

    My eyes don’t roll when I read the word “regression” but they do glaze over. I still manage to understand most of your articles, I’m just not smart enough to catch it if your wrong but I have manged to use the Pythagorean theory once or twice though when I had a good pencil and a new notebook.

    Reply
  • Michael Terry March 28, 2014, 1:58 pm

    My only objection when I read these analyses of fumble recoveries being random is that people will think that it’s a law of nature and can be no other way. The fact that fumble recovery rates aren’t correlated from year to year in aggregate doesn’t prove that no teams (or no single team) are better at it than others (and not just by chance). It’s hard to prove with statistical methods that an outlier isn’t just chance.

    But, more, it’s definitely not proof that a team cannot influence fumble recovery outcomes. When you watch football games, you’ll see many players giving up on plays early because they’re “too far” from the ball or are celebrating a sack or are unproductively hand fighting with an opponent or etc. It’s easy to imagine a coach making a priority, and incentivizing, always going to the ball and looking for fumble recovery opportunities, no matter how unlikely the opportunity seems to be. We don’t need statistics to understand that more alert people around the ball means a higher rate of fumble recoveries. Fumbles aren’t magically distributing themselves evenly between the teams.

    The history of sports is rife with new techniques or new emphasis making previously uncontrollable outcomes controllable.

    Reply
    • wiesengrund March 28, 2014, 7:06 pm

      Say hello to Lovie Smith.

      Reply
  • Andrew Healy March 29, 2014, 2:31 pm

    If you plot the distribution of fumble recovery rates, it’s pretty amazing how close it is to a bell curve with just 32 obs, which may be evidence of randomness (not that we really need any more).

    Reply
  • Jeff from Indy May 19, 2014, 9:49 am

    Charles – This is a very interesting perspective on fumbles and expanded my horizon on the topic

    However, you’re Opp Fumbles Recovered calculations are using an incorrect recovery factor of .476 vs .524

    If 47.6% of fumbles are recovered by the Offense, the 52.4% are recovered by the Defense

    The sum (at the bottom) of the Fumbles Lost and Opp Fumbles Lost must equal 20.5 – instead they equal 19.6

    Using the 52.4% recovery rate, Opp Fumbles Lost will be 10.7 and the sum will be 20.5, as it MUST be

    This factor has also been used incorrectly in the FR Expected logic and line of thought

    Regards – Jeff from Indy

    Reply

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