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The Giants, Dolphins, and Simpson’s Paradox

This year, the Giants are averaging 6.35 net yards per pass and 4.18 yards per carry. That’s below-average on both counts, as New York ranks 20th in both categories.

This year, the Dolphins are averaging 6.53 net yards per pass and 4.30 yards per carry. Miami ranks 15th in NY/A and 17th in YPC.

And yet the Giants are averaging more yards per play this year than Miami! How is that possible — after all, plays are just rushes or passes (including sacks), and the Dolphins are averaging more yards per pass and yards per rush. But New York has gained 5.70 yards per play this year, while Miami is averaging only 5.58 yards per play.

The answer, of course, is Simpson’s Paradox. We can also see an example of Simpson’s Paradox with Chicago. This year, the Bears are averaging 6.65 net yards per pass and 4.45 yards per carry. That’s above-average in both categories, as Chicago ranks 12th in both metrics. And yet the Bears rank below the Giants in yards per play, at just 5.65.

This is because the Giants pass a lot, and passes are more effective at gaining yards (even net of sacks) than rushes. The Giants have passed on a league-high 70% of plays, while Miami has passed on 58% of plays and the Bears just 54% of plays.

This happens with a few teams every year. The Jaguars are averaging 6.02 net yards per pass, 4.25 yards per rush, and 5.41 yards per play. The Redskins are averaging 6.12 net yards per pass and 4.33 yards per rush, and yet… Washington is only averaging 5.34 yards per play, a lower average than Jacksonville. That’s because the Jags have passed on 66% of plays, while the Redskins have passed on only 56% of plays.

The table below shows where each team this season ranks in net yards per pass, yards per carry, and overall yards per play.

Y/P RkTmNY/AYPCYd/PlayNY/A RkYPC RkPass Perc
1Kansas City Chiefs8.644.727.052859.5%
2Los Angeles Chargers8.355.166.963256.4%
3Los Angeles Rams8.734.786.891653.4%
4Tampa Bay Buccaneers7.993.776.5242965.1%
5Atlanta Falcons7.764.076.4562464.6%
6Pittsburgh Steelers7.364.346.2771463.7%
7New Orleans Saints7.973.926.1852756%
8Green Bay Packers6.694.86.0710567.2%
9Denver Broncos6.355.165.8919161.6%
10Carolina Panthers6.355.115.818356%
11New England Patriots7.14.055.7982557.1%
12Minnesota Vikings6.574.195.77141966.3%
13Cincinnati Bengals6.454.395.73161364.9%
14Oakland Raiders6.664.115.71112162.7%
15New York Giants6.354.185.7202070%
16San Francisco 49ers6.364.775.6517755%
17Chicago Bears6.654.455.65121254.5%
18Houston Texans7.093.955.6392653.6%
19Detroit Lions6.254.485.6211163.1%
20Miami Dolphins6.534.35.58151757.6%
21Indianapolis Colts5.984.685.5126963.7%
22Seattle Seahawks6.594.325.44131649.2%
23Philadelphia Eagles6.234.15.42222261.6%
24Jacksonville Jaguars6.024.255.41251865.6%
25Washington Redskins6.124.335.34231556.3%
26Dallas Cowboys5.674.845.328455.5%
27Baltimore Ravens6.043.615.16243163.8%
28New York Jets5.824.085.06272356.3%
29Cleveland Browns5.214.544.95301060.9%
30Tennessee Titans5.663.864.8292852.5%
31Arizona Cardinals4.893.354.32313262.7%
32Buffalo Bills4.193.73.98323057.8%

This is why it is not useful to rank teams by yards per play (or, by extension, yards). The 2018 Giants and 2018 Dolphins (or Bears, or 49ers) show why.

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