Dome Football Teams Really Are Worse Playing Outdoors

It has been a long-held belief that NFL teams that usually play their home games in a dome, do worse in the playoffs when they have to play outdoors. Thus making home field advantage (HFA) even more important for dome teams. It's also been a go-to reason as to why Drew Brees and Peyton Manning play worse outdoors, especially late in their career in cold weather.

I used the home/away results from the past 13 seasons (not including the 2020 season-to-date), and flagged whether each team played their home games in a dome or not.

The overall HFA has been 2.41 points per game - games in a dome have been slightly higher, at 2.68 points per game, with games in open air (outdoors) stadiums at 2.29 points per game.

Dome teams specifically have faired even worse when playing in an open air stadium - losing by 2.64 points, on average. However, open air teams playing other open air teams see an HFA of 2.29 - so the difference between the two is the incremental difference for dome teams: 0.34 points per game, which is significant across 3,161 games.

Description	HFA
Overall HFA	2.41
Dome Teams, in Dome	2.68
Dome Teams, in Open	-2.64
Open Teams, in Open	2.29
Open Teams, in Dome	-2.34

The real question is how is this enhanced in the postseason? Overall, HFA increases to 4.35, with dome teams enjoying a higher HFA of 5.03 (in the regular season it's only 2.52). However, when those same dome teams have to play on the road outdoors? Their average margin falls to a massive -11.31 points per playoff game.

Comparing this to their advantage in the regular season is a total swing of 13.83, basically two full touchdowns. But compared to their increased advantage in the postseason? It's even more pronounced, for a 16.34 points per game swing (4.35 PPG - -11.31 PPG). So the increased focus on clinching home field is truly necessary for dome teams.

Description	HFA	Count
Overall Postseason	4.35	130
Open Teams, in Open, Postseason	4.09	95
Dome Teams, in Dome, Postseason	5.03	35
Dome Teams, in Dome, Regular Season	2.52	845
Dome Teams, in Open, Postseason	-11.31	26

For a final wrinkle, I also looked at teams that moved within their market between dome/open air stadiums. So teams like the Atlanta Falcons (moved from dome to dome in 2017) and Los Angeles Rams (moved from St. Louis to LA in 2016) don't count.

That left the Dallas Cowboys and the Minnesota Vikings (who actually went from dome to open in 2014, then back to a dome in 2016):

Blue: Open; Green: Dome

There doesn't appear to be much correlation in the above chart over only two teams, as the relative quality of the team over time appears to be the larger driver than moving between stadiums.