Defense and Special Teams: Field Position Matters

Nov 11, 2012; Seattle, WA, USA; Seattle Seahawks defensive end Bruce Irvin (51) celebrates a sack against the New York Jets during the third quarter at CenturyLink Field. Mandatory Credit: Joe Nicholson-USA TODAY Sports

My statistical study of 2012 defenses continues. I’m still trying to wrap my brain around the mathematics of all that drive data I posted a couple days ago. There’s plenty of good information there, but I can’t regress the data to wins without first accounting for offense and special teams. Doing that expands the data set ad infinitum, which removes the validity of what I was hoping to find.

There’s a way to do this, and I’ll find it. I’m just not there yet.

In the interim, I’ve decided to look into the last variable I can think that of needs to be addressed in this study. That would be the starting field position for opposing offense. The reasoning is pretty simple, give the offense a shorter field, and they’re likely to score points more often.

Below is the average starting field position for each team’s defensive drives. (There’s probably a better way to word that.) I expected the Seahawks to be near the top of the list, and sure enough they are there at #1.

My first thought when I saw the results was that the difference between the best (Seattle, 24.2 yard line) and the worst (Phily, 31.86 yard line) wasn’t enough to matter. It’s only 7 yards, right? Then I realized the cumulative effect that the difference could have over almost 200 possessions.

To show that, I calculated the difference in total yards over the entire season. Putting these numbers in perspective, the Eagles almost spotted their opponents Marshawn Lynch’s entire rushing production for the year, and that’s before those opponents ever ran a play. That’s a lot of yards being given to their opponents for free over the course of the season.

I have to say, the Seahawk’s special teams don’t get nearly the credit they deserve for being great last season. We know the Seahawks defense was among the best, and the Seahawk offense was as well at the end of the year. The special teams units get overlooked though, and that’s a shame. One look at the “total yards” column below, and it’s easy to see how important they are to the success of this team.

Special teams aren’t the only factor here in creating this average starting field position, though they are the biggest factor. Each team’s offense played a roll as well, since turnovers tend to be the cause for the shortest of the short-field scenarios. I don’t actually have the data, but I’d wager that teams who’s offenses have a high percentage of 3-and-outs are mostly down near the bottom of this list as well.

I’m probably going to have to collect all this same data for the offenses just to see how it comes up. It wont have any bearing on this study of defensive variables, but it’ll be very interesting.

What does all of this mean for the defenses? That’s simple. Good special teams can help inflate how good a defense is perceived to be. If the defense is already great, then forcing the opponent to travel farther to get points is just mean.

The Seahawks are apparently mean. I can live with that.


Rk Team Ave. LOS Drives total yards
1 Seattle Seahawks 24.2 164 0
2 San Francisco 49ers 24.9 173 121.1
3 Indianapolis Colts 24.98 173 134.94
4 Atlanta Falcons 25.1 176 158.4
5 Cincinnati Bengals 25.46 186 234.36
6 New England Patriots 25.6 191 267.4
7 Denver Broncos 25.75 186 288.3
8 Chicago Bears 25.95 192 336
9 Green Bay Packers 25.96 184 323.84
10 San Diego Chargers 26.13 176 339.68
11 Dallas Cowboys 26.21 168 337.68
12 Tampa Bay Buccaneers 26.42 187 415.14
13 Baltimore Ravens 27.02 190 535.8
14 Cleveland Browns 27.14 194 570.36
15 Minnesota Vikings 27.26 181 553.86
16 Jacksonville Jaguars 27.55 183 613.05
17 Washington Redskins 27.63 177 607.11
18 Arizona Cardinals 27.66 205 709.3
19 Miami Dolphins 27.7 178 623
20 New York Giants 27.84 170 618.8
21 Kansas City Chiefs 27.98 173 653.94
22 Houston Texans 27.98 196 740.88
23 New York Jets 28.39 187 783.53
24 Carolina Panthers 28.65 170 756.5
25 New Orleans Saints 29.32 187 957.44
26 St. Louis Rams 29.59 176 948.64
27 Detroit Lions 29.59 185 997.15
28 Pittsburgh Steelers 29.87 174 986.58
29 Tennessee Titans 30.04 184 1074.56
30 Buffalo Bills 30.21 179 1075.79
31 Oakland Raiders 30.87 180 1200.6
32 Philadelphia Eagles 31.86 176 1348.16

* All starting field position data was provided by Football Outsiders! I didn’t have the time to go though all the game logs to collect this particular data, so I owe them a huge thank you for making this data available.

Topics: Seattle Seahawks

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  • Paul

    Your original thought was that the few number of drives initiated against the Seahawks may have made the defense look better than it actually was. If you divide total points scored by the number of drives, you’ll get points per drive. The Seattle defense ranks well in points given up per drive. If you divide yards given up by the number of drives, you get yards surrendered per drive. I haven’t checked that, but the hawk defense probably scores less well with that metric. The “per drive” numbers remove the variable of the number of drives for various defenses.
    There’s a lot that “averages” don’t tell you. If the opponent kicks a field goal, that’s three points that the defense gave up. If the other team recovered the ball on the 20 yard line and ran three plays for no gain and kicked the field goal, those points aren’t really on the defense. The other team was in field goal range when they got the ball.
    There’s a lot of luck in football. An awfully lot of things almost happen – Balls almost caught or almost dropped, tackles almost made, or not – flags almost thrown or not, etc. That means that there’s a lot of “luck” in the raw numbers, which means that the calculations aren’t definative. The points given up per drive metric, however ranks all the best teams at the top and all the worst teams at the bottom. It’s a pretty good indicator or quality. Points given up per drive, might be the best you can do in figuring out how good a defense is. It will be fun to see what you come up with.

    • 12thMan_Rising

      I never believed that the Seahawk’s defense wasn’t among the league’s best. The problem is that, analytically, the tools that suggest that are flawed in some pretty obvious ways. What I’m trying to do is show that being #1 is scoring defense is a factor of both the quality of the defense, as well as some things that the defense doesn’t control. Once we determine all those factors, I’m going to mathematically eliminate them so we’ll have an evaluation tool that accurately describes the quality of a team’s defensive play.

      As for the luck element, these things will be washed out with a large enough sample size. A full season is enough to remove most of those effects, though not completely. Once I have a good idea of the relationships for all these variables, and all the data I will need, then I’ll expand the data set to include the previous decade. That will eliminate out all of the “luck” elements

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