Unfair advantage because of artificial turf? Sorry Mourinho, but data says no

An extended analysis of over 1000 football matches in Switzerland shows that there is no evidence that teams with artificial turf perform better at home.

Artificial turf has always been controversal in football. While football purists see the synthetic grounds simply as a treason to the game, there are also ongoing discussions about whether teams gain an unfair advantage because of it. The hypothesis is that the home advantage increases for teams who play in stadiums with artificial grass because they are more used to it. Also, there is an ongoing debate if playing on artificial turf leads to more injuries.

“I dont understand how you can play the best European competition on artificial surfaces. It’s not easy for people who are not used to it. There is a fear in the duels from players who are used to playing on good surfaces in England.”

Jose Mourinho after the game against YB in Champions League 18/19. Manchester United still won 3-0.

In Switzerland, there are quite a few teams whose stadium has an artificial pitch. Most notably BSC Young Boys, who won the championship in the last two seasons. Besides YB, there are five other teams in the two strongest leagues with an artificial turf: Neuchâtel Xamax, FC Thun, FC Schaffhausen, FC Wil and SC Kriens (since last season).

We have analyzed over 1’000 matches from Super League and Challenge League in the last three seasons to check out if there really exists an advantage for the “synthetic” teams.

First, let’s check out the home performance of every team:

Teams with grey bars play on artificial turf. YB was clearly the strongest team in the last three seasons.

The chart shows that YB performed very strong at home in the last three years, with an average of 2.54 points. Second comes FC Basel with an average of 2.2 points – they play on natural grass.

Of course, the chart tells us nothing significant about the effects of artificial turf. YB performing strong at home could have several reasons. They were the strongest team in the last two seasons, after all, not only at home, but also away.

To get to the heart of the matter we have to take a look at the home advantage. For this, we simply take the difference between the average points won at home and away of every team.

Rapperswil-Jona surprisingly has the biggest home advantage, followed by YB.

Now things become clearer. The biggest home advantage belongs to FC Rapperswil-Jona. They won 0.58 points more at home.

BSC Young Boys indeed has a very strong home advantage, too. They score 0.56 points more in Stade de Suisse.

Just by looking at the chart, you can already see that there is no real indiciation that the home advantage of teams with artificial turf (grey bars) is particulary strong. FC Schaffhausen, FC Wil and Neuchâtel Xamax have an average home advantage. FC Thun, despite playing on synthetic ground, performs only slightly better at home.

A very special case is SC Kriens. They performed actually considerably worse in their home stadium. They play in their new stadium with artificial turf since last season – and actually scored 0.33 points less than in their away games. But because they only got relegated last season to Challenge League, the sample is with just 36 matches rather small.

To test if the home advantage of the teams with artificial turf differs significantly from the others, we perform a Welch Two Sample t-test. We compare the average home advantages of the two groups:

The t-test shows no significant difference between the artificial and natural groups.

As suspected, no significant difference could be found. Actually, with an average home advantage of +0.25 points, the teams who play on natural grass even perform slightly better in their own stadium than the ones who play on artificial turf (+0.19 points). But since the p-value is 0.72 and not even close to >0.05, we can safely say that artificial grounds have no impact on the home advantage.

So sorry Mister Mourinho, but data clearly indicates that you are wrong. There may be other reasons to hate artificial grass, but it does not give the teams an unfair advantage.

Leave a Reply