Most football gamblers know that home-field advantage is traditionally worth three points in the eyes of oddsmakers. But in a 2020 that began with Tom Brady and Bill Belichick losing in the first round of the postseason at home, only to see the entire sports world upended due to the pandemic, this is the calendar year for questioning things we have always believed to be certainties.
“This year, we’re probably only really concerned with the length of travel,” Roar Digital / BetMGM VP of Trading Jason Scott said. “If two local teams are playing, we’re not putting any real premium on the home team.”
With roughly half of NFL teams playing in empty stadiums and the other half allowing fans at minimal capacities, home teams are 90-85-1 this year: the lowest home winning percentage since 1972.
What’s strange is that Power Five college football teams are winning at home more frequently than in any recent season. For many reasons, college football and the NFL don’t make for an apples-to-apples comparison—there are differences in parity, and more colleges are allowing the full 25% fan capacity than NFL teams—but the juxtaposition is noteworthy nonetheless.
Zooming out to the larger pro sports landscape, the NFL appears to be the oddball. In MLS, teams still went 127-68-58 at home in 2020 despite only a few playing in front of fans. MLB played its regular season without fans entirely and saw the largest league-wide home-field advantage in a decade.
Back in July, Sportico accurately predicted that MLB home-field advantage would be unaffected by a lack of fans. We theorized that familiarity with home facilities and environmental factors were largely responsible for creating the advantage, citing the fact that the Colorado Rockies, Denver Nuggets and Denver Broncos experience the largest boosts from playing at home in their respective leagues, likely due to Denver’s unusually high altitude. Additionally, our analysis of prior MLB seasons revealed no correlation between average fan attendance and home winning percentage.
While it’s certainly plausible that empty stadiums have an effect on NFL teams that they don’t have on baseball teams, soccer teams or even collegiate football teams, it seems more likely that something else is at play. In fact, the disappearance of home-field advantage began not this year, but last year.
It is possible that last year was simply an outlier, and that this season’s low number is indeed due to a lack of fans. But, in addition to that explanation being statistically unlikely, penalty numbers indicate that the absence of fans isn’t impacting the game in intuitive ways.
A classic explanation for the existence of football’s home-field advantage is that crowd noise disrupts visiting offenses, sometimes rendering them unable to hear the quarterback’s play calls or snap counts. If this were the case, one would expect away teams to consistently be called for more false start penalties than home teams. Home teams, however, were called for more false starts in each of the last eight seasons, whereas in 2020, away teams have been called for more false starts, yet have fared just fine in terms of game outcomes.
One might have anticipated that referees would favor home teams less than usual this year given reduced pressure from home crowds. “Subconsciously, the cheering does affect them,” Scott said. “We see that in every league, in every sport, globally. The home team gets a better deal over time in terms of calls.”
This season, though, 48.7% of all penalties have been called on home teams, a minimal increase from the 48.4% average over the previous five seasons.
The evidence points towards a multi-year trend of diminishing home-field advantage caused by more than simply a reduction in fan attendance during the pandemic. That cause, whether better technology, diet and travel habits for road teams, or something else, remains elusive.
Sportsbooks made massive adjustments to their lines in response to the data from last season. In 2019, home teams only covered the spread 44% of the time, the lowest number ever, even though home teams were favored by an average of just 1.76 points–the third lowest number of all-time, per ESPN.
This year, bookies realized they had to go further. They’ve favored home teams by an average of only 1.43 points, and home teams have subsequently bounced back to cover 49% of the time. “[Last season’s results were] a huge factor, probably more than COVID,” Scott said. “Guys doing models were already starting to question home field advantage, so it made it easier when COVID came along to throw it out, except for the big east coast (to) west coast trips.”
Indeed, travel may be the primary driver of whatever smidgen of home-field advantage still exists. Road teams are 45-56 this year when traveling to a different time zone, but have a winning record of 30-26-1 when staying within the same time zone or coming off a bye week. “If [a team is] crossing the country, there’s certainly something there that’s been proven over a long time,” Scott said. “Worth maybe two or three points.”
In 2021, sportsbooks will potentially have to weigh the return of fans to stadiums against the body of facts indicating that reduced home-field advantage may not be related to fans’ absence in the first place. Scott says next season will likely be treated in the same way as 2020. “I think we’ll start like that, and we’ll find out if the trend goes against us,” Scott said.