Do Home Teams Even Need Fans?

New pandemic research finds that home teams are doing worse without crowds in some leagues but better in others. What's going on?

On February 2, 2007, a hooligan riot at a soccer game in Sicily spilled out into the streets, injuring around a hundred people and leaving a police officer dead. The Italian government responded by banning fans from any stadium that hadn’t bothered to comply with with safety standards, which at the time was pretty much all of them. For a few weeks matches went on in front of empty seats. “This is not football,” Roberto Mancini complained after Inter played its first ghost game. “We might as well quit right here and start again in September.”

For researchers interested in home advantage, though, it very much was football, played by the usual teams under all the usual conditions except one: the effect of the crowd. Across 24 games from the top two divisions—an unimaginably large sample of closed-door games at the time—they found that referees were less likely to help home teams with fouls, yellow cards, and red cards than when fans were in the stands. “Soccer referees are supposed to be neutral,” the authors of one paper wrote, but instead it appears officials “change their behavior under influence of social pressure.”

Home teams win more games. This basic truth holds up across sports, across leagues, even across centuries. It’s even truer in soccer, which has a higher home win percentage than basketball, baseball, hockey, or American football. But after decades of highly educated head scratching, nobody’s sure exactly why soccer teams are better at home. Evidence for popular explanations like jet lag or the comforts of the familiar is mixed at best, so recent work has tended to look more at the impact of the home crowd.

Some of these crowd effect studies have been pretty clever, like the one that found referees were more likely to judge that a video clip was a foul if they heard fans react to it. But since crowd effects don’t seem to be directly linked to crowd size—for some mysterious reason, the Championship has a slightly higher home advantage than the Premier League—it’s not easy to study in the real world. You’d need a natural experiment like those Italian closed door games where the crowd vanished entirely while everything else stayed the same. Ideally you’d want it to happen across lots of different leagues for lots of games, maybe even long enough that the psychological novelty wore off and crowd-free games became the new normal.

Ideally, from a research point of view, you’d want a global pandemic.

“I don’t think we’ve ever seen, in any sport, as many games as we did when all of a sudden no fans are allowed, when normally you have tens of thousands of fans packed into stadiums,” says Luke Benz, who authored a new paper on soccer’s home advantage with Michael Lopez, the NFL’s director of data analytics. The gigantic new data set has already inspired at least 14 papers on soccer home advantage before and after COVID-19, and for the most part they’ve reached the same conclusion: when fans aren’t around, home teams get fewer calls and are less likely to win than under normal conditions.

So do home teams pick up more points because refs cave to crowd pressure? Lopez says that question is “hard to simplify.” To get a more detailed picture of what’s going on, their paper measures home advantage in terms of yellow cards and goals on a league-by-league basis. “Before the pandemic, all these leagues had different home advantages,” Benz points out. “In Greece, for example, they had the highest home advantage in terms of goals, and it was about two and a half times the advantage in Austria, which had the smallest. We hypothesized that some leagues might change a lot and some leagues might change a little.”

Their results are delightfully messy. During the pandemic, 15 of the 17 European leagues they looked at saw a decline in yellow card home advantage compared to the five previous seasons, which is what you’d expect if fans were influencing refs’ decisions. On the other hand, home teams in six leagues were more likely to outscore opponents in ghost games than back when the stands were full. In the Premier League and Serie A, home teams were actually better off in terms of both goals and yellow cards without their pesky fans around. But the most interesting leagues might be the four where reffing and results moved in opposite directions: home teams got fewer calls but won by more goals. Huh?

One thing to note here is Benz and Lopez aren’t just counting up cards and goals per 90’ before and after the world stopped. What makes their paper different from the other, less ambiguous COVID studies is buried in its methodology section. Most researchers model home advantage using plain old linear regression. Benz and Lopez prefer something called Bayesian bivariate Poisson regression, which offers a better fit for soccer data, and their new and improved numbers suggest we can’t blame the refs for everything.

“What that says is maybe the reason for the home advantage in the first place was not so much because of the referees as much as it was player behavior,” Benz explains. “If it were all on the referees we might expect to see more of a carryover between the yellow card outcome and the goals outcome.”

Compared to a referee giving free throws to a shooting guard or free yards to a wide receiver whose catch was interfered with, it’s less clear how much your garden variety soccer infractions matter to the scoreline. Red cards and penalties have an outsized impact, sure, but fouls and yellow cards? Harder to say. One 2011 paper found that yellow cards were correlated with a significantly lower win percentage for home teams but not, for some reason, away teams; fouls actually went the other way, where committing more appeared to be linked to winning. Even if the story about home crowds bullying refs into helping their team win is true, it might only be one big call every couple games that makes a difference.

So why do soccer teams still lose more games away from home even now, in the time of COVID, under the all-seeing eye of VAR? One possibility is that they do it to themselves. Pre-pandemic research shows that home teams don’t just get more calls, they play better soccer, breaking lines more often and spending more time near the opponent’s goal. Away teams tend to press less and be more direct in possession. A detailed study of one club over the course of a Serie A season found that its away games were marked by different tactics and “difficulty in creating and establishing stable structures of play,” which jibes with the experience of anyone who’s ever watched their team struggle through the proverbial cold rainy night at Stoke. Another paper adjusted English managers’ stats by league and season and found that some, like Harry Redknapp, seemed to enjoy a stronger home advantage over the course of their career than others. It could be that there’s some self-fulfilling prophecy to how teams change their style depending on where they play, though as always there’s just too much going on in soccer to draw sweeping conclusions about causes and effects.

The ability to isolate some variables in that mess is exactly what makes natural experiments like the Italian closed-door games or COVID-19 valuable for research, and the thousands of new ghost games should teach us more about home advantage in the next few years. But this once-in-a-lifetime data comes with its own complications: midseason stoppages, crowded schedules, quarantine absences, rule changes, and the psychological toll of it all. “A lot of people say ‘We observed this home advantage due to no fans,’” Benz says. “And our statement is kind of like, well, we observed this home advantage due to there not being fans and also the unprecedented conditions under which teams lived for several months.”  ❧

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Further reading:

• Luke Benz and Michael Lopez, Estimating the change in soccer's home advantage during the Covid-19 pandemic using bivariate Poisson regression (2020)
• J. James Reade et al., Echoes: what happens when football is played behind closed doors? (2020)
• Per Petterson-Lidbom and Mikael Priks, Behavior under social pressure: empty Italian stadiums and referee bias (2007)
• Alan Nevil and Roger Holder, Home Advantage in Sport: An Overview of Studies on the Advantage of Playing at Home (Sports Medicine 1999)
• Richard Pollard and Gregory Pollard, Home Advantage in Soccer: A Review of Its Existence and Causes (International Journal of Soccer and Science 2005)
• Richard Pollard and Gregory Pollard, Long-term trends in home advantage in professional team sports in North America and England (1876 – 2003) (Journal of Sports Sciences 2005)
• Alan Nevill et al., The Influence of Crowd Noise and Experience upon Refereeing Decisions in Football (Psychology of Sports and Exercise 2002)
• Anne Anders and Kurt Rotthoff, Yellow Cards: Do They Matter? (Journal of Quantitative Analysis in Sports 2011)
• Javier Fernandez-Navarro et al., Influence of contextual variables on styles of play in soccer (International Journal of Performance Analysis in Sport 2018)
• Barbara Diana et al., How Game Location Affects Soccer Performance: T-Pattern Analysis of Attack Actions in Home and Away Matches (Frontiers in Psychology 2017)
• Thomas Peeters and Jan van Ours, Seasonal Home Advantage in English Professional Football; 1974–2018 (De Economist 2020)

Image: Markus Spiske, Olympic Stadium Munich