Home Advantage in Soccer

“Welcome to Hell” and “RIP Manchester” banners greeted Manchester United’s players as they arrived in Istanbul to face Galatasaray. Manchester United was the heavy favorite but needed a win in order to advance onto the next round of the 1993 Champion’s League. One threatening bellboy, a few disturbing prank calls and one rogue and violent policeman later, the game ended in a draw. Manchester United was eliminated, simultaneously shocking soccer fans throughout the world and displaying the power of home advantage. Home advantage is a term often used in modern sports to describe the advantage home teams have over their opposition. It is especially prominent in today’s global society in which teams travel all over the world to play each other. Although home advantage is an abstract psychological concept, it operates in tangible ways. My research will demonstrate how different aspects of soccer collaborate to influence players, referees, and ultimately, the outcome of a match.

In soccer, it is the job of the referee to discipline players and maintain order by impartially calling fouls and penalties, issuing yellow and red cards, and deciding how much extra time to add. However, that is rarely the case. According to data compiled from 128 Italian soccer games, referees favor home teams. In each game, referees awarded, on average, 2.69 yellow cards, .27 red cards, and .17 penalties for each team. However, the home team’s average was 2.65 yellow cards, .23 red cards, and .2 penalties while the away team averaged 2.73 yellow cards, .31 red cards, and .15 penalties (Scoppa and Schwartz, 2014). These statistics are alarming because any one of those decisions has the potential the change the outcome of more than one game. If a player receives two yellow cards or one red, his team will be forced to play the remaining minutes of the game with one less player. When a team wins a penalty, 76.8% of the time it is a goal (Hawerchuk, 2010). Furthermore, another study discovered that when deciding how much extra time to add, the referee’s decision tends to favor the home team. In the Bundesliga (German Soccer League), and the Major League Soccer (MLS), when the home team losing by a goal, extra time is, on average, 11% longer than when they are winning by a goal. The most notable example of this home bias would be the German team, Stuttgart. When they are winning, the average added time is 2 minutes and 22 seconds, when they are losing it is 3 minutes and 43 seconds. The difference is 1 minute and 21 seconds, or 57% (Bialik, 2014). While such small numbers may appear insignificant, it is important to remember that it only takes a few seconds to score a goal. Therefore, if a team is winning, it is beneficial to have less added time, but if they are losing, the more time, the better. Additionally, the implications of these results are worrisome. A referee has to make many split-second decisions without the aid of his assistants or technology. There are no replays to help him decide and whatever his decision is, it is final, so any mistake or bias cannot be corrected. As these studies have demonstrated, referees are biased, so the question is no longer if they favor the home team, but why?

A commonly held belief about home advantage is that through their support, fans elevate athletic performance, thus contributing to home advantage. However, this theory is only partially correct. Instead of affecting players and their performances, crowd pressure and density influences the referees. In 1993, professor Simo Salimen analyzed 56 matches where one team was playing at home but the crowd was neutral so that the support for both team was roughly equal. He discovered that the home team did indeed score more goals than the visiting team when the crowd supported them; they still scored more even when the crowd supported the other team (Salimen, 1993). Additionally, a professor named Alan Nevill conducted an experiment where he divided 40 referees into two groups of 20. Then he had them watch a replay of the 1998 game between Liverpool and Leicester that took place in Anfield, Liverpool’s home stadium. One group watched the recording with noise while the other group watched in silence. While they were watching the game, Nevill had them decide if 47 different incidents were fouls or not. The group that watched with noise, where the crowd supported Liverpool, called 15.5% less fouls against Liverpool than the silent group (Ingle, 2013). While the results of Salimen’s research contradict the idea that the crowd affects players, Nevill’s experiment clearly indicates that the crowd can influence the referee’s decision making. This is problematic because a referee is just as capable as any player at changing the outcome of a match.

Unlike the psychological advantage caused by a combination of referees and fans, traveling creates a physiological advantage for the home team. This advantage is caused by changes in climate and geography and the act of traveling itself. When teams travel to play away, they often travel to locations where the climate is different than their home locations. Since soccer is a global sport, these locations and climates vary drastically, to the extent that it sometimes interferes with players’ physical capabilities. For example, during the 2014 World Cup in Brazil, the International Federation of Association Football (FIFA) had to implement mandatory water breaks for the first time in World Cup history in order to prevent dehydration (Murray, 2014). However, water breaks in soccer are a recent innovation. Before the 2014 World Cup, players had to play at temperatures much higher than they normally played at without breaks. Since there were no breaks, players had two options: to drink while play continued or go without water. Both options put them at a disadvantage, while the players accustomed to the climate, normally the ones playing at home, have an advantage. Furthermore, a lack of fluids can cause many physiological problems such as dehydration, cramping, heat exhaustion, and in extreme cases, heat stroke (Epstein, 2000). These health problems and their symptoms greatly limit the capabilities of players. For example, symptoms of dehydration include headaches, dizziness, and rapid breathing. If a player has a headache and a muscle cramp because he is not used to the heat and is unable to drink enough fluids, he will be at a severe disadvantage when competing with someone used to the climate.

Similarly to climate, changes in geography, specifically altitude, can have a profound effect on a player’s performance. During a 2014 World Cup qualification match between Argentina and Bolivia in La Paz, Bolivia, the effects of altitudes were especially evident. Argentina was the clear favorite and was ranked 3rd in the world, while Bolivia was ranked 37th and had world-class stars such as Lionel Messi, Javier Mascherano, and Angel Di Maria, who all play in Spain: Messi and Mascherano in Barcelona and Di Maria in Madrid. However, despite their difference in ranks, the game ended in a 1-1 draw. While this result could have occurred for many reasons, Messi, the captain of Argentina, later claimed it was because of the altitude. In an interview, Messi said:

It is terrible to play here at altitude, so a draw is a good result for us. Every time you make an effort or play at high pace, you need time to recover. Some of the players had a headache and others felt a bit dizzy.” (Sport, 2013)

La Paz is 3,640 meters above sea level while Madrid is 667 meters above sea level, and Barcelona is even lower at 12 meters above sea level. This large difference in altitude caused many Argentinian players to suffer from altitude sickness, which is when the body cannot get enough oxygen at high altitudes because it is not used to the thinner air. This can results in tiredness, dizziness, vomiting, and headaches (Clinic Staff). During the game, many Argentinian players were visibly suffering from altitude sickness. Di Maria and Mascherano required the use of oxygen masks and Messi vomited. Furthermore, all three players were unable to play for a week after returning to Spain (Sport, 2013). Additionally, a University of Oxford researcher, Patrick McSharry, analyzed the results and statistics of 1,460 international matches at varying altitudes in 10 different countries. McSharry’s research revealed that with every 1,000-meter increase in altitude, the goal difference increase by half a goal, in favor of the home team. He was also able to calculate the home win percentage at different altitude differences. If both teams are from the same altitude, the home team will win 53.7% of the time. At an altitude difference of 3,695 meters, such as in the case of Bolivia and Brazil, the home team, Bolivia, has a 82.5% of winning (BMJ, 2008). Altitude difference is a huge component in traveling’s contribution to home advantage because it can severely handicap some players, preventing them from performing at their best, without hindering the abilities of others.

Lastly, traveling itself can cause home advantage to occur, especially long distance traveling. The act of traveling contributes to home advantage mainly by causing fatigue and unsettling the traveling players. Studies conducted in Germany have shown that a team’s performance, measured in goals scored and conceded, has an inverse relationship with distance traveled. They found that the amount of goals scored away from home in each game is not affected by distance traveled for 17 out of 18 clubs participating in the 1986-87 and 2006-2007 Bundesliga. However, the same studies also found that as the travel distance increases for most teams, the amount of goals they concede also increases. The average distance traveled and goals conceded for an away game is 368.33 kilometers and 1.71 goals. Examples of this trend are Berlin, which travels on average 541.77 kilometers while conceding 2.65 goals, and Bayer 04 Leverkusen, which on average travels 285.08 kilometers and concedes 1.45 goals. (Oberhofer, 2010). This pattern is a result of the physiological impact traveling, specifically flying, has on the human body. The farther teams travel, the longer they are on a plane. Flying requires players to travel in a confined space, at high altitudes and lower atmospheric pressure, all while breathing recycled air with low humidity. Fifty percent of the air in planes is recycled while the humidity is, on average, only 20%, well outside the normal 40-70% range. These factors can result in dehydration and makes players more vulnerable to infection and illness.

Another aspect of flying is that it confines people to one, low pressurized location. Low pressure and lack of movement has been found to cause dizziness and increase the risk of deep-vein thrombosis (DVT), or blood clots. DVT is caused by sluggish blood movement which itself is caused by periods of long inactivity, 4 hours or more. DVT can cause pain, swelling, and in rare cases, the death of the affected person (Trend, 2002). Another negative effect of traveling is the physical and mental fatigue caused by lack of proper sleep. According to Dr. Ellenbogen, proper, restful sleep is almost impossible to come by on airplanes because people are forced to sleep sitting upright, which forces our body, specifically our neck, to stay tense (Kugel, 2011). Sleep deprivation is a serious problem for players because it can lead to weight gain, depression, delayed reaction speed, and trouble concentrating (Matta, 2013). If a player gains weight, he will be less physically capable. Combined with delayed reactions and concentration, that player will end up being a liability to his team. By hampering a player’s physical and mental effectiveness, traveling gives the home team a physiological home advantage.

While referees, fans, and traveling are the most obvious contributors to home advantage, another, less glamorous, contributor is field composition. In recent times, some clubs have decided to replace their natural grass fields with ones composed of artificial turf. Unfortunately, artificial turf fields have been proven to increase the rate of injuries and cause health problems. A study focused on injury rates and types among female soccer players discovered that 8.7 injuries occur, on average, every 1000 hours of game time or training on an artificial surface compared to the 8.3 injuries from playing on natural grass field. Furthermore, according to the same study, sprains, re-injuries, ankle injuries, and long-term injuries (>21 days) are more common on artificial turf. For every 1000 hours on artificial turf, there are 4.6 sprains, 2.1 re-injuries, 4.0 ankle injuries, and 3.3 long-term injuries. Meanwhile, on a grass field, there are 3.3 sprains, 1.4 re-injuries, 3.0 ankle injuries, and 1.7 long-term injuries every 1000 hours (Steffen, 2007). Unfortunately, while the statistics gathered by this study indicate that injuries are more frequent on artificial surfaces, it provides no explanation on why that is the case. However, an article on usatoday.com about the 2015 Women’s World Cup provides both an anecdotal reasoning and a scientific explanation on how artificial surfaces increase injury rates. In this article, Alex Morgan complained about having to play on an artificial surface:

Not only are they long lasting injuries, but there are long-term effects of playing on turf. The achiness, taking longer to recover than on natural grass, the tendons and ligaments are, for me at least, I feel more sore after turf. It takes longer to recover from a turf field than natural grass. (Litman, 2014)

Furthermore, she blamed her teammate Nikki Marshall’s season-ending injury on artificial turf. According to Morgan, “Nikki Marshall tore her ACL after getting ‘caught in the turf’ while planting her foot. The turf didn’t give like natural grass would have” (Litman, 2014). This claimed is further supported by Dr. Michael Freitas, the team doctor for the Western New York Flash, which plays on turf. Dr. Freitas said:

When your foot hits the grass and you twist, your foot is going to come out of contact with the ground easier than it would on an artificial surface. When your foot hits turf, that rotation is then taken up in your ligament, which can rupture, as opposed to your foot breaking contact with the grass, which allows that force to be dissipated. (Litman, 2014)

According to this testimony, the very act of kicking a ball has different results on the body depending on the field composition, so players will have to adjust accordingly or risk getting injured. As a result, the players who have to adjust less or are already accustomed to playing on that surface, namely the home team, will have an advantage. Another possible explanation for the increase in injuries would be the increase in fatigue as a result of playing on turf. A prominent property of artificial turf is that it absorbs heat, which results in higher field surface temperatures. A case study of the University of Missouri’s artificial turf field recorded that the average surface temperature of the field at “head-level” was 138 degrees when the actual temperature was only 98 degrees (Fact Sheet). This can lead to effects similar to playing at higher temperatures, such as dehydration, heat stroke, and dizziness, which will limit a player’s performance. Regardless of the causes, artificial surfaces have been statistically proven to increase injuries, which is problematic because any injury can change the outcome of a game and the course of a player’s career. When a player is injured, the coach is forced to make a substitution, but if he has none left, the team has to play with one less player. This is unfortunate because the fear of injury, unfamiliarity with the field, and increased fatigue due to heat will often make players more hesitant in their actions and decisions, and as a result, the team more accustomed to the field gains an advantage.

While the previous paragraphs and findings clearly demonstrate that home teams have an advantage, they do not mention how much impact these components have on the outcome of a match. In other words, how effective is home advantage? Recent analysis of the statistics of the Premier League from 2009 to 2013 found that the participating teams home win percentage was 47% while their away win percentage was 27%. In the 2012-2013 Premier League, 15 out of 20 teams had better home records then away (Atkins, 2013). Furthermore, home advantage is also prevalent in international soccer. By analyzing nearly 9000 games between 1993 and 2004, researchers have found that, on average, international teams win 50.3% of the time at home while losing 25.1 percent of the time. The remaining 24.6% of games end in draws (Koning, 2008). Based on these studies, the power of home advantage is clearly evident. Winning almost half the time at home is a significant advantage, especially in professional leagues where every point is important and a win is worth 3 points, a draw is worth 1, and a loss is worth 0 points. The strength of a team’s home advantage is an important factor on whether or not a team will win a trophy. However, while these studies demonstrate the impact and presence of home advantage, they do not explain the impact of each component of home advantage because it is impossible to analyze the role of each component separately based on past statistics.

While home advantage is a psychological phenomenon commonly accepted to be true, the majority of its supporters are unaware of how it works or its actual effects. In this paper, I analyzed how different aspects of aspects of soccer interact to create advantages for the home team. These findings all support that, despite it being an intangible concept, home advantage has many tangible mechanisms that can be altered to make soccer a fairer sport where outcomes are decided by skill alone. Fortunately, FIFA has already many steps to make its competitions more balanced by introducing new technology that helps referees make calls, such as goal line technology, and by utilizing a two legged-fixture format, which forces teams to play each other twice—both home and away. While these are promising steps in the right direction, there are many more possible changes that could be implemented to reduce the power of home advantage but aren’t because of economical or traditional reasons. For example, replays could easily be added but FIFA is reluctant to do so because they believe it will change the nature of soccer. While it is unfortunate that more changes aren’t made to weaken home advantage, fans and players alike have embraced it as another aspect of soccer. For better or worse, home advantage is now a part of soccer, the most popular sport in the world.