May 11, 2020
May 11, 2020

How will playing behind closed doors affect soccer matches?

Home advantage behind closed doors

Home advantage factors

Problems and opportunity

How will playing behind closed doors affect soccer matches?

With games likely to be behind closed doors, bettors will be assessing how the lack of spectators will affect the market. What impact will playing matches behind closed doors have on soccer matches? Read on to find out.

Home advantage behind closed doors

The primary bettors are likely to consider concerning games behind closed doors is the concept of home advantage.

I have written previously about home field advantage in soccer betting with home teams enjoying an advantage of 0.25 to 0.5 goals and with Pinnacle’s closing line odds implying a home win percentage of around 45% across Europe’s top five leagues.

The big question is how much of the existence of home advantage we can attribute to the partisan crowd.

Home advantage factors

My previous article on home advantage broke down the possibilities for its existence into a few parts. How playing behind closed doors impacts upon each of them could go some way towards isolating it's effect.

The home crowd and refereeing

In a previous article, I suggested that VAR data could show the potential impact of a home crowd on refereeing.

In theory, VAR should be objective and not swayed by crowd noise so any fall in the ratio between home and away penalties awarded could suggest that officiating is indeed altered by the presence of the home crowd.

There is also some scientific evidence of the crowd having an impact on official’s decision making.

In one study, 40 referees were asked to officiate a recording of Liverpool's match with Leicester at Anfield during the 1998-99 season. Twenty watched the fixture with the crowd noise whilst the other twenty watched a silent version.

The referees exposed to the crowd noise were less likely to penalise the home team with fouls than the referees watching the silenced game footage. This echoes the findings from analyzing the effect of VAR on penalties awarded to the home team.

Obviously this is the area which we would expect games without a crowd to be influenced the most.

Familiarity and territoriality

There is some evidence that a team’s familiarity with a venue can contribute to home field advantage. It has been described as a possible instinctive improvement in performance as the away team is comparable to invaders to your territory.

In one study home teams were found to have heightened testosterone levels which corroborates previous findings concerning hormone levels, home advantage and territoriality.

Other suggestions that may contribute to home advantage include familiarity with the stadium and field dimensions, which is an especially compelling argument in Major League Baseball for example.

These factors are present regardless of the presence of home fans which strongly suggests home advantage would still be in existence behind closed doors.

Travel

The effect of travel is a logical factor behind home advantage but would not be affected if games were to be played normally behind closed doors. This would still be worth monitoring if venues were changed to some degree.

Home advantage in matches played behind closed doors

We do have some recent examples of games played behind closed doors prior to the suspension of soccer. Most recently Europa League, Champions League and Serie A games were all played without fans in the stadium.

The issue with isolating the effect of home advantage on these games is that the sample size is very small and the noise created by other factors such as first leg results, matchups and lineups is substantial.

As an example of some of the difficulties faced in Serie A this season, the home win percentage implied by Pinnacle’s odds was actually higher for the home teams which feels completely counterintuitive. A look at the league position of the teams that took part in these fixtures gives an indication as to why this would be the case:

Fixture

League position home team

League position away team

Juventus vs Inter Milan

1

3

Sassuolo vs Brescia

11

20

Milan vs Genoa

7

17

Parma vs Spal

9

19

As you can see the round of fixtures played behind closed doors just happened to contain fixtures for which all of the away sides were inferior to the home team. This included the two lowest ranked sides in the league playing away from home.

It’s essentially impossible to draw many conclusions from this since comparing the implied home win percentage against the average from Serie A this season would be completely misleading.

Opening and closing line: Attempting to see more

One way to attempt to get around such a difficulty is to use the opening and closing lines for fixtures that were arranged to take place with fans in the ground but actually took place without them. This allows us to see how the odds move as home advantage possibly gets reduced.

Fortunately one such set of fixtures does exist. Four Europa League round of 16 first leg matches were arranged to be played with fans before being changed to behind closed doors fixtures nearer to the event.

Fixture

Implied opening line probability

Implied closing line probability

Difference in home win likelihood

Olympiacos vs Wolves

38.61%

33.78%

-4.83%

Wolfsburg vs Shakhtar Donetsk

47.17%

57.45%

10.28%

Eintrackt Frankfurt vs Basel

61.39%

59.59%

-1.80%

LASK vs Mancheter United

26.74%

21.10%

-5.64%

As you can see in three of the four matches the home team’s implied win probability was reduced by the time the event started. However the Wolfsburg vs Shakhtar Donetsk fixture actually saw a significant shift toward the home side despite the lack of fans.

One factor which may have contributed to this is that Shakhtar fielded an arguably understrength side due to injuries to Stepanenko and Tite, two of their better players. Wolfsburg also fielded a perhaps stronger than expected team.

This presents a large and perhaps insurmountable problem with the data set used here. If lineup changes and other factors can move the line towards the home team, negating any potential loss of home advantage, then how can we attribute the swing towards the away side to loss of home advantage?

Are the odds on behind closed doors matches efficienct

The other issue with attempting to look at the fixtures in this way is that we are assuming the odds are efficient in the first place. Arguably if the opening odds were efficient then, in the case of these Europa League games, the probability of the match being moved behind closed doors may have been factored in already to some extent.

There have been occasions when odds have not necessarily reflected the probabilities they convey due to niche circumstances and lack of information. It is certainly arguable that this is such a niche circumstance.

The fact that all of the home teams failed to win in those European fixtures, including Frankfurt surprisingly being defeated heavily by Basel, could be indicative that maybe the odds were inefficient ahead of these matches. Still, the sample size is far too small to get anywhere near to being confident in a conclusion like that.

Problems and opportunity

Whilst it might be disappointing to not actually be able to isolate the impact playing behind closed doors has on home field advantage, it should actually be a good thing for bettors that it is difficult to do so.

We know from the evidence of the home crowd biasing referees that home advantage should be reduced, it is just that the extent of this is difficult to isolate.

Since it is difficult to factor the home advantage effect into the odds then there may be an opportunity for a bettor to secure some value before the market is able to rediscover efficiency when it comes to home advantage. It could be an enjoyable area to study in the meantime.

Read more soccer betting articles before making use of Pinnacle's soccer betting odds.

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