When the COVID-19 pandemic kept most fans out of NFL stadiums in 2020, home-field advantage was shut out, too: Road teams won more than home teams for the first time since the AFL-NFL merger. In 2021, crowds are back — but the advantage isn’t.
Through Week 8, NFL road teams are 63-56, a .529 win percentage.1 What’s more, the oddsmakers haven’t fully caught up to this trend: After years of figuring in a 2-to-3-point advantage for home teams, they’re 51-67-1 (.433 cover percentage) against the spread, per ESPN’s Stats & Information Group. Anyone who had just bet on every road team this year would have beaten the house over 56 percent of the time, on par with long-term averages for professional bettors!
To find out where home-field advantage went (and if it’s ever coming back), we need to figure out what the advantage actually is.
The last time FiveThirtyEight studied NFL home-field advantage in 2018, all the usual suspects were examined: the strain of travel, the effects of crowd noise on players and officials, even stadium altitude. No clear answer emerged, though director of NFL analytics (and former FiveThirtyEight contributor) Michael Lopez identified high-leverage officiating calls as one potential culprit.
But ESPN Stats & Information penalty data doesn’t bear that out. Tracking 12 different penalties (plus total number of calls and total yards assessed) before, during and after the fan-limited 2020 season returned no clear answers. For example, the difference between home and road defensive pass-interference calls strongly correlated with home-field advantage, pre-COVID-19. That makes sense, as defensive pass interference is a high-leverage call — but the penalty was called even more frequently against road teams in 2020 and 2021, and road teams went 188-183-1 (.507) across that span.
Home-field advantage is usually measured across the entire league. But it’s well-known that some teams’ crowds get louder than others; Kansas City Chiefs fans at record-holding Arrowhead Stadium almost certainly confer more advantage than often-outnumbered Los Angeles Chargers fans did at the 30,000-seat StubHub Center/Dignity Health Sports Park during the three seasons the Chargers played there. So if home-field advantage isn’t distributed evenly among teams, maybe all teams haven’t been equally affected.
Using FiveThirtyEight’s Elo model, we can compare each team’s home and away results against the expected scoring margin for each matchup — giving us a per-team home/road strength differential that takes strength of schedule into account. Here’s the adjusted home-field advantage for all NFL teams, and how that’s translated into win rates, across the decade prior to COVID-19:2
There’s a lot to unpack here, from the Green Bay Packers’ massive 8.45-point difference in adjusted scoring margin to the Dallas Cowboys winning just one more game at home than on the road. Scoring margin should always correlate strongly with win rate, and it does — but there are some interesting deviations. The Cleveland Browns had the eighth-smallest home scoring advantage but the fourth-biggest home/road win differential, suggesting that FirstEnergy Stadium crowds gave the Browns the edge in a lot of close pre-pandemic games. Their rival Pittsburgh Steelers had the second-biggest home scoring boost — but since they boasted an impressive .589 road-win percentage over this period, Heinz Field accounted for only the 21st-biggest boost in win rate. The New York Jets had the third-biggest home-field scoring advantage, while the New York Giants — who play in the same stadium — had the fourth-smallest.
But how has each team’s home-field advantage changed over the last two years?
Two notes of caution: First, the 2020-21 data is extremely noisy, as pandemic protocols affected almost everything about how NFL teams practiced for, traveled to and played games. Different stadiums had different numbers of fans, COVID-19 outbreaks had massive, unbalanced effects on individual games, and empty stadiums had unpredictable (and largely un-trackable) impacts.
Second: “Home-field advantage,” in betting parlance, means how much better than their opponent a team is expected to be when playing at their stadium as opposed to a neutral site. So because the New York Jets have been 11.6 points better at home than on the road over the past two seasons, adjusted for schedule, MetLife Stadium can be said to grant a home-field advantage of half that difference: +5.8 points ... at least, when the Jets are playing in it.
The Jets are one of six teams that have actually increased their home-field scoring advantage during the pandemic, along with the Tampa Bay Buccaneers, Houston Texans, Cleveland Browns, Seattle Seahawks and Tennessee Titans (though the last two by less than 0.2 points each). But 26 have seen their home advantages decrease, and 19 of those by more than 3 points.
Most importantly for the leaguewide average, many of these big drops hit teams that had enjoyed the biggest pre-pandemic advantages. Twelve of the top 15 home scoring-margin differential teams saw their margin drop by at least a field goal — including four teams with double-digit point decreases.
The hardest hit? The San Francisco 49ers, who had played 6.7 points per game better at home than on the road from 2010 to 2019. Since then, they’ve played 13.1 points per game worse at Levi’s Stadium than on the road. That’s a stunning drop, turning the 49ers’ typical +3.4-point home-field advantage into a -6.6-point disadvantage.
Before COVID-19, every team was at least a little bit better at home than on the road. But over the past two years, 14 teams have negative adjusted home-field scoring-margin differentials. Even if we throw out the 2020 data and focus only on 2021’s partial results, the pattern holds: Fifteen are in the negative. Oddsmakers have been adjusting home lines downward from the old 3-point rule of thumb for years, but there would have been no way to predict that half the league would drop below zero.
We still haven’t found exactly what causes home-field advantage in the NFL. But it’s important to understand that it’s always varied quite a bit from town to town and team to team — and the impacts of COVID-19 on home-field performance have been even more varied, and much more dramatic.
Neil Paine contributed research.
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