It’s statistically proven that playing at home gives the players a huge advantage.
But do you know the reason?
Well to be fair, no one does. But there sure are some very interesting theories.
Statistics (Home : Away)
Those statistics are the results of a study analyzing the English Premier League in the years between 1992 and 2005
Goal average: 1.5 — 1.1
Yellow cards: 1.1 — 1.6
Red Cards: 0.06 — 0.09
Penalties converted: 0.1 — 0.05
Blame The Poor Referee
Statistically, referees are more likely to favor the home team even after eliminating the effects of the crowd by awarding fouls, cards, and penalty kicks.
Adding the jeering of the fans when every player happens to trip over his own laces and you can see how biased a referee can be.
Another study indicates that stronger teams tend to be favored by referees. Also many referees don’t believe in the saying "innocent until proven guilty", and are heavily swayed by players and team's reputations.
This can somewhat explain why teams at the top of the league get many dodgy calls in their favor, while smaller and more physical teams can get bullied by some referees.
Because those big teams perform well, referees subconsciously assume that player X who plays for this magnificent club is too talented to try and dive to get a point from humble team Y (unless he’s Ronaldo).
Good Old Steroids
The natural steroids, not the illegal ones.
Studies showed that the levels of testosterone in the players' bodies increase by 50% when playing at home and this percentage is even higher when they play against arch-rivals.
Testosterone is one of the most popular doping agents among athletes and any increase in its levels in circulations greatly affects both the physical and mental performances of the players.
This increase is possibly because of the primal instinct in males to "defend their territories", which in this case are their home stadiums.
It also appears that a larger crowd makes the home team play more aggressively, which may indicate that the fans also help increase the testosterone levels.
My House My Rules
Another widely accepted factor is the fact that a change in routine for the travelling team also puts them at a disadvantage.
Sure, some people think players are just being softies, but I'm sure you grumble and moan when their is too much milk in your coffee and claim your whole day is ruined.
Imagine what the players have to go through every other week.
Traveling, sleeping in hotels, being out of their elements can harm the players’ mental and physical strength, and lead them to under-perform.
—The level of bias differs between referees so don’t be quick to point fingers. Consider the possibility that maybe your team’s players really are thugs.
—The amount of home advantage decreases in lower divisions; probably because those divisions have smaller crowds.
—It’s the size of the crowd that seems to make a difference, not the density.
—"Home advantage" is a good and valid excuse you can use when your team loses. Just pick the right time to use it and don’t abuse the excuse, or else you will be called a whiner.