The value of 'home comforts'

rugby365.com columnist Anton van der Merwe takes a look at how much value should be placed on 'home ground advantage' as we approach the final weekend of this year's Super 14 league stages.

When it comes to selling houses there is one refrain that applies universally: location, location, location. 

In this edition of Statistically Speaking we look at the role of location (i.e., home field advantage) in the Super 14.  The final week of league play is left and only the Bulls know where they will be playing their play-off game(s).  The five teams vying for a semi-final spot do so with the potential of securing a home semi-final.  The outcome of the Bulls vs Stormers game will have a big say in the home field stakes.

How much is at stake? A number of aspects make up home field advantage, some of which are very hard to quantify.  Factors like the crowd, the weather, the pitch surface, etc.  all play some role.  For most of these there are no real hard data.  The analysis below is therefore limited to two aspects one can glean from the stats namely, (1) the win-loss ration based on location, and (2) the influence of the referee.

The latter has a slightly bizarre twist to it, which the Super 14 fans that listen to the New Zealand commentators might well have picked up.  That is the notion that the home team ought to be cut more slack than the visiting team.  We will explore to what extent the stats show this phenomenon to be prevalent in the Super 14. 

Win-Loss Ratios Local and Abroad

The first graph shows the overall winning percentage for home games vs away games.

Teams are almost twice as likely to win at home than what they are when playing away.  Home field is clearly a significant advantage.  The question becomes whether factors like crowd, weather and pitch really have that significant of an impact or whether some other factors are in play.  The stats reveal that there is more to home field advantage than just the characteristics inherent in the location.
 
The Referee's Influence

The first graph highlights the referee's influence when it comes to home and away stats with the ratio of yellow cards awarded to home teams vs away teams.

The ratio here is almost one to two!  That is, away teams are almost twice as likely to be yellow carded than home teams.  Unfortunately, the total number of yellow card data points are relatively small and digging into them does not lead to conclusive analysis.

However, a similar trend emerges when one compares the kicks conceded (penalties and free kicks) between home and away teams.  A total of 1,940 kicks have been conceded in the Super 14 competition.  The percentage increase in kicks conceded  that away teams are subjected to over home teams is depicted in the next graph.  

On average away teams are on the receiving end of 14.8 percent more penalties and free kicks than home teams.  Moreover, South African and New Zealand away teams seems to get a particularly raw deal in this regard.

Drilling a little further into the data one can eliminate the stats for local derbies and consider the stats only for away games in foreign countries.  That is, one can for example attempt to answer the question whether New Zealand teams playing in South Africa or South African teams playing in Australia always get the short end of the stick.  The next three graphs provide the details on kicks conceded per game for teams from each country for their home games compared to games in the two foreign countries.

There is a lot in these graphs.  However, two things stand out.  South African teams playing in Australia (28 percent increase) and New Zealand teams playing in South Africa (32 percent increase) seems to really get the short end of the stick.  Moreover, one could also point out that Australian teams playing at New Zealand venues do better than at home and New Zealand teams playing at Australian venues do better then most on the kicks conceded front.

These conclusions run foul of one assumption namely, that national referees officiate all games in their respective countries.  This is of course not he case and the referee dimension has to feature in the analysis.  Take for example the New Zealand teams' stats when playing in South Africa and officiated by New Zealand referees.  New Zealand referees penalized New Zealand teams playing in South Africa with 14.5 conceded kicks per game (more than any other country's referees). 

Conversely, in those same games New Zealand referees penalize South African teams with only 9.0 kicks per game!  This is not the most egregious example, South African teams get nailed with 16.8 kicks conceded per game when playing at Australian venues.  Bulls fans might very well point to Craig Joubert's handling of the Bulls vs Reds game in Brisbane that resulted in 14 kicks conceded for the Bulls.

This trend where local teams are judged differently from visiting teams is prevalent throughout the home and away stats.

Why This is Bad (Very Bad) for Rugby…

Are the refs under pressure to please the home crowd?  After all, people pay good money to see their team win – nobody loves (or want to pay) to see a looser.  But what about the rugby contest?  Is the game now rather about the good-guy home team and villain visiting team?  This smacks of World Wrestling Federation (WWF) antics where the emotional reaction of the crowd trumps the essence of skill and the rugby contest!  Once one understand where all of this is coming from you also have the answer to the question about booing the kicker, that is so prevalent now – something that never occurred in rugby.

I might be revealing my age here, but how many of us remember cordial applause for a brilliant piece of rugby – even by ones staunchest rugby foe.  Where has civility in the rugby public gone?  Quite frankly, it followed officiating into the cesspool when refs morphed into local Tom, Dick and Harry pleasers.  If the powers that be is prepared to officiate the game like a WWF farce why should the crowd behave as if it is something noble…