The Seahawks and the NFL’s Best Home Field Advantage

by Andrew Mooney

A road game in the NFL can be a daunting proposition. Facing a sufficiently amped home crowd, a team has to worry about things they normally wouldn’t at home: snap counts, hearing play calls, and hey, what is that biker-looking gentleman doing with a blown-up picture of my family? Every NFL fan base would like to believe its savage passion is the most intense in the league, but there can’t be 32 best home field advantages. To that end, I set about finding which team’s home field gives them the largest boost.

First, I don’t think it makes sense to attribute the effects of a team’s home field advantage solely to the fans; you can’t separate the noise they make from the environment in which they make it, the stadium. It’s possible that fans in Seattle truly go bananas for the Seahawks, but the stadium’s architecture (or even its PA system) likely contributes at least some part to pumping up the volume at CenturyLink Field. Similarly, Boston fans exhibit plenty of passion and noise at Celtics, Bruins, and Red Sox games. Why should they be so notoriously quiet for the Patriots, unless Gillette Stadium itself (or, I suppose, the commute there) muted them?

For that reason, I centered my analysis on which team’s stadium the combined effect of the building and the fans produces the greatest home field advantage. Instead of using home and away win-loss records, I looked up teams’ point differentials at home and on the road from the time they moved into their current stadium, using the ultra-handy Play Index at Pro Football Reference. (There is considerable evidence that point differentials provide a more reliable measure of team quality than do simple wins and losses.)

Next, I calculated the difference between each team’s point differential at home and on the road, then divided that by the number of seasons the team has occupied its stadium. This gave me the average number of additional points per season provided by a team’s home field advantage. The Chargers have played in what is now Qualcomm Stadium since 1967, but assuming the home field advantage effect it affords has been constant over that time, its per-season average should be as valid as that of Philadelphia’s Lincoln Financial Field, which began hosting NFL play in 2003. Finally, in order to ensure that I had a sufficient sample of games, I omitted teams who moved into a new stadium within the last five seasons, which included the Colts, the Jets, the Giants, and the Cowboys. I also counted the major overhaul to Soldier Field in 2003 as a new stadium, given the way it drastically altered the building’s structure. My results are presented below.

This analysis bears out the conventional wisdom, at least at the extremes: Seattle enjoys the greatest home field advantage in the NFL, and Gillette Stadium ranks at the bottom of the league. Recently, the Ravens have borne out that M&T Bank Stadium is one of the hardest places to play in the country; they currently boast the NFL’s longest home winning streak at 13 games.

It’s surprising to see the Superdome so low, with its at least anecdotal status as one of the loudest stadiums in the NFL. The top ten features only three enclosed stadiums, and not necessarily the ones you expect Ford Field, the Edward Jones Dome, and the Metrodome. Again, team quality over this time should have nothing to do with the final outcome, since we’re comparing the same teams’ home and away results.

So what’s the deal with Gillette? As Chris Gasper noted a couple of years ago, the stadium itself is largely to blame: its open-ended architecture doesn’t hold sound well, its location forces everyone to rush for the exits to avoid traffic once the result is assured, and it’s one of the priciest stadiums in the NFL, especially when you factor in transportation costs to get there. Mr. Kraft may be happy with the money the place rakes in, but if he wanted to give an assist to his product on the field, he might consider phasing out the wine-and-cheese folks and drawing a slightly more populist crowd.

This post can also be seen on Boston.com here.