Borussia Dortmund's famous Sudtribune, better known as the "Yellow Wall," was silent. As Bayern Munich's Joshua Kimmich scooped the ball over Borussia Dortmund goalkeeper Roman Burki's head for what proved to be the winning goal, it was greeted by sporadic shouts of glee from the Bayern players and an echoic silence from what would normally be an immersive, claustrophobic atmosphere. Dortmund would then usually go up a gear and throw everything and the kitchen sink back at Bayern Munich. But not this time.

Teams in all sports have always drawn on home support for an extra boost; the crowd are, in essence, a "12th man" on the sideline. But with matches being played behind closed doors due to the coronavirus outbreak and the usually bouncing stands replaced by a strict number of security guards and engineers, teams failing to take any advantage from home comforts has become a familiar narrative. No longer do they have that roar after conceding, or that feeling like with Liverpool's famous Kop, where the fans create an atmosphere as if they're sucking the ball into the net. Instead, as the home team looks for inspiration, they're met with silence, clapping and the odd shout from the sideline.

Since the Bundesliga returned in front of empty stands, where they call them the "ghost games" ("geisterspiele"), home teams have won 21.7% of matches (10 from 46 games), down from 43.3% before the shutdown of play in March. Home teams have also scored fewer goals -- the pre-lockdown rate of 1.75 goals per game is now down to 1.28 -- while the away teams' winning ratio has risen from 34.83% to 47.8%. The same trends have been seen in Estonia (after 29 games there were just 11 home wins) and Czech Republic (after 32 games, just 10 home wins) since their leagues resumed when behind closed doors.

"I don't think that [the change in fortunes at home] is a coincidence," Leverkusen boss Peter Bosz said. "It's easier for the away teams when there are no fans in the stadium. Without spectators, it comes down more to the quality of players."

As the other top European leagues plot their return, those battling relegation will be mindful of what Freiburg coach Christian Streich said recently: "For us [smaller teams], the absence of fans hurts us more than it does the top teams." Eintracht Frankfurt boss Adi Huetter agreed with Streich, saying: "Teams with a high level of technical quality ... are less dependent on support. This disadvantages some teams more than others."

"The vibe is a little bit off"

Away from the mere psychological boost or hindrance served by thousands of fans either cheering you on or doing their utmost to put you off your game, there are mathematical trends in the differences between games played with and without crowds. Three scorecasting economics professors (Carl Singleton, James Reade both from the University of Reading and Dominik Schreyer, WHU, Otto Beisheim School of Management) have been analysing these numbers in their work-in-progress paper "Echoes: What happens when football is played behind closed doors." Their study shows how teams have traditionally won 46% of their matches in front of their home support. After analysing 191 matches played behind closed doors in Europe's top competitions since 1945, this figure falls to 36%.

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To look behind the numbers, they analysed three factors: players, coaches and referees behaving differently to how they usually would when playing in front of packed stands. Through plotting the form behind closed-door matches since 2002, away teams received 0.5 fewer yellow cards than normal and missed fewer penalties, while the home teams scored fewer goals. There was also less injury time awarded.

Their paper, which is still being researched, has the following summary of their findings: "We have found that the commonly observed home advantage in sport is almost completely removed when spectators are not present, and we find some suggestive evidence that this is because of the removal of the influence of spectators on the referee; almost half a yellow card less is given to visiting players, while less injury time is awarded."

The Bundesliga referees have spoken about the difference of officiating in these "geisterspiele" with Deniz Aytekin, who took charge of Borussia Dortmund vs. Schalke 04 -- a huge local derby -- revealing the effect it had on Aytekin personally.

"I have to admit that in the derby a week ago, I had pulse rates that were extremely low compared to games with spectators," Aytekin told German broadcaster ZDF. "Suddenly, these emotions are missing, which is just as elementary for us because ultimately we, too, live this passion."

For the players, it has been a jarring experience. "The vibe is a little bit off to be fair," RB Leipzig's Tyler Adams told ESPN. "But it's one of those things where you have to dig deep and really try to grind out the results, because to run that extra 15 yards without the fans cheering for you is definitely difficult sometimes. Those are the people you play for, and they give you that extra motivation. In a sense it feels like preseason games with no fans. It's a weird vibe in the stadium with the echoes, communication and everything."

It remains to be seen whether the small sample pool of the Bundesliga and the trends there will transfer to the other leagues, or if it was just an anomaly that is possible when you bring in the past 130 years of football.

How this could impact the rest of the 2019-20 season

While the Premier League looks cut and dry at the top, with Liverpool expected to win the title sooner rather than later, the battle to avoid the drop is still ferocious. Just eight points separate Norwich in 20th (21 points after 29 games) and Brighton in 15th. ESPN sources say those teams fighting toward the bottom of the table are concerned about the "integrity" of the league, given the differing circumstances in how matches were played before and after lockdown. This was one argument against neutral grounds -- ultimately an idea dropped except for a handful of games involving the league's top teams -- being used, but the Premier League clubs' analysts are playing close attention to any trends emanating from the Bundesliga.

For a team such as Norwich City, they've collected 15 points at their Carrow Road home this season, but just six on the road. Their fellow relegation battlers Aston Villa in 19th have six of their remaining 10 games at home -- they can no longer draw on inspiration from an empty Holte End.

There are some teams that are better away from home -- like in Serie A, teams such as AC Milan, Internazionale, Roma and Fiorentina have fared better on the road this season (Roma have won 0.23 more points away than they have at the Stadio Olimpico). Playing without pressure and expectation on home turf may now be liberating.

In Spain, La Liga is set to resume before the Premier League and Serie A, on June 11 with Sevilla vs. Real Betis. Adding to the uncertainty are Real Madrid and Levante's decisions to play their remaining home matches away from their usual stadiums, as the Santiago Bernabeu and Ciutat de Valencia are both being redeveloped. Real Madrid will play at their training ground, Alfredo di Stefano stadium, but Levante will need to travel 90 miles to play their home matches in La Nucia.

But like in the Premier League, it is the teams near the foot of the table who are concerned about what they have witnessed in the Bundesliga.

Real Valladolid are 15th in La Liga and four points off the relegation zone. Their next two matches are against rivals at the bottom Leganés (a) and Celta (h). "It's a reality that has an impact ... against Celta and Leganes," captain Javi Moyano said. "Against Celta we'll be playing for our future, and we'd like 24 [thousand] or 25,000 [supporters] there with us.

"It's a handicap playing behind closed doors... Maybe it evens things up between both teams. Home advantage is important in [La Liga]. If you're not prepared mentally for being in an empty stadium... it could feel like you're in training. Whoever knows how to maintain their level of attention and concentration will win."

In "What you think about football is wrong," Kevin Moore writes how home advantage has steadily declined as the game as evolved. Back in the in 1895-96 season of the English football leagues, teams won 64.6% of home matches. In the 2015-16 season, across all four divisions, this was down to 41% -- in part due to tactical adaption for home and away matches. But while sample sizes and pools of research can be microanalysed for those at the wrong end of the table, playing in front of empty stands mean they can no longer make "home" an uncomfortable experience for the visiting team, while those at the top end will also have to adjust without the intimidating Kop or Yellow Wall.

Former Bayern Munich and Germany midfielder Bastian Schweinsteiger was once asked what he was most afraid of. He replied: "The Yellow Wall." Gio Reyna has made his first steps in the Bundesliga with Borussia Dortmund, and when you listen to his perspectives on the home atmosphere in Dortmund, you understand what the club have lost with the stands now lying silent.

"It really feels like there's an extra few players on your team and you ... can feel the intimidation for the other team," Reyna told ESPN. After Dortmund beat Schalke in their first match back after the lockdown, the players went and saluted the empty Sudtribune. But that sight of the home team smiling and joking as the match finishes and leaving familiar surroundings with three points secured has become far less common since "geisterspiele" became the new normal.