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Who Were The Luckiest NFL Teams In 2011?

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Almost half of the 256 games played in the 2011 regular season were decided by seven points or less, 125 games to be exact. A little over a quarter of all games (67) were decided by 4 points or less.

In many games, the outcome was determined by a single play. Cowboys fans know this all too well: missed extra points, the self-icing of a kicker, a single route run slightly off target - it felt like the Cowboys got the short end of the stick quite a lot in 2011.

Eight Cowboys games were decided by 4 points or less, the third highest total in the league. The Cowboys finished 4-4 in those close games. Only the Broncos and Cardinals had more of these close games (9) and finished with a 6-3 and 5-4 record respectively. So does this mean the Cowboys were luckier than other NFL teams? Or unluckier?

Good news for everybody who's ever pondered this conundrum: a little bit of simple math can help us find the answer.

But before we do the math, here's an overview of the teams with the best and worst W/L record in games decided by four points or less.

Team W/L W/L % Team W/L W/L %
BAL, GB, NO 2-0 1.000 Vikings 1-4 0.200
Giants 5-1 0.833 Seahawks 1-4 0.200
Steelers 4-1 0.800 Dolphins 1-5 0.167
Lions 3-1 0.750 Panthers 0-2 0.000
Broncos 6-3 0.667 Eagles 0-3 0.000

On to some hard numbers:

If you've been on this blog for a while, you're familiar with the Pythagorean Formula. If not, here is what it is: The formula was originally developed by the godfather of baseball stats, Bill James, who surmised that a team's true strength could be measured more accurately by looking at points scored and points allowed, rather than by looking at wins and losses.

The formula was later revised by Daryl Morey (then a statistician for STATS, Inc., since 2007 General Manager of the Houston Rockets) , who developed the following NFL version of the formula:

Points Scored2.37
Points Scored2.37 + Points Allowed2.37

When Morey adapted the formula to football, he ran a regression against the results of the previous ten years, and ended up with 2.37 as the most accurate exponent based on that specific 10-year period. Other people have tested the formula against other periods and have come up with different exponents, but the 2.37 has stuck around and is the most commonly used exponent today. Football Outsiders still use the 2.37, and if it’s good enough for them, it’s good enough for me.

The formula calculates the projected wins for a team based on points scored and points allowed. Applied at the end of the season, it can tell you which teams won or lost more games than they "should" have. Teams that won more games than the formula provides for are considered lucky, teams that lost more games than projected are unlucky.

Here's the full list of teams ranked by their level of luck, as measured by the variance between actual and projected wins in 2011:

Team Points
Green Bay 560 359 201 15 11.9 3.1
Kansas City 212 338 -126 7 4.0 3.0
Denver 309 390 -81 8 5.8 2.2
Oakland 359 433 -74 8 6.3 1.7
New England 513 342 171 13 11.6 1.4
New York Giants 394 400 -6 9 7.9 1.1
Arizona 312 348 -36 8 7.0 1.0
New Orleans 547 339 208 13 12.1 0.9
Baltimore 378 266 112 12 11.2 0.8
Pittsburgh 325 227 98 12 11.2 0.8
Tennessee 325 317 8 9 8.2 0.8
San Francisco 380 229 151 13 12.3 0.7
Atlanta 402 350 52 10 9.3 0.7
Tampa Bay 287 494 -207 4 3.5 0.5
Cincinnati 344 323 21 9 8.6 0.4
Detroit 474 387 87 10 9.9 0.1
Jacksonville 243 329 -86 5 5.2 -0.2
St. Louis 193 407 -214 2 2.3 -0.3
Chicago 353 341 12 8 8.3 -0.3
New York Jets 377 363 14 8 8.4 -0.4
Buffalo 372 434 -62 6 6.6 -0.6
Dallas 369 347 22 8 8.6 -0.6
San Diego 406 377 29 8 8.7 -0.7
Washington 288 367 -79 5 5.8 -0.8
Houston 381 278 103 10 10.9 -0.9
Cleveland 218 307 -89 4 4.9 -0.9
Seattle 321 315 6 7 8.2 -1.2
Indianapolis 243 430 -187 2 3.3 -1.3
Carolina 406 429 -23 6 7.5 -1.5
Philadelphia 396 328 68 8 9.8 -1.8
Miami 329 313 16 6 8.5 -2.5
Minnesota 340 449 -109 3 5.5 -2.5

Let's look at the Cowboys in a little more detail. The Cowboys ranked 15th in the league in points scored with 369, and ranked 16th in points allowed with 347. That's pretty middle-of-the-road any way you look at it, and their record of 8-8 also reflects this. The formula projected the Cowboys for 8.6 wins, so it would be fair to say that the Cowboys weren't slightly unlucky compared to other teams.

As for the other teams, the formula suggests that the Packers, Chiefs and Broncos were the luckiest teams last year, all recording about two more wins than their points total would suggest. At the other end of the spectrum, the Vikings and Dolphins finished about two games lower than where the formula projected them. These two were easily the unluckiest teams in the league last year.

Interestingly, I wrote a post after week two last season, and after two weeks, the formula was already projecting the Cowboys for an 8-8 finish. In 2010, I did the exact same exercise after two weeks, and at the time, the projection for the Cowboys was 4.5 wins, not far off their eventual six-win total. And although the formula did jump around in subsequent weeks during both seasons, you can be sure that I'll run the same post after week two of the 2012 season.

For most teams, these numbers tend to change from year to year. But not for all. The Cowboys have had a negative variance for the last three years in a row. No team has had more successive years of 'bad luck', with the Texans and Panthers the only other teams to also have had three consecutive years with a negative variance.

On a personal level, I have long felt that the Giants are the luckiest teams in sports and 2011 was certainly no exception. The Giants finished with a positive variance for the seventh year in a row. The next closest teams are the Cardinals with four consecutive years and the Saints with three consecutive years. Only once in the last ten years (2004) did the Giants have a negative variance. The Giants are lucky on a metaphysical level that transcends rational numbers. And please spare me all that motivational-poster-nonsense about how "luck is what happens when preparation meets opportunity" or some other overused cliché like that.

Both the Cowboys and the Giants are at the extreme ends of the statistical probability bell curve. The odds are that this will change in 2012. Some people may attribute this to Lady Luck coming or going, others may talk about regression to the mean, others yet couldn't care less about some fancy formula. But one thing looks pretty sure: things should only get better for the Cowboys.