Tuesday, November 1, 2011

Away Teams Pay the Penalty

Chris Anderson has another excellent post at Soccer By The Numbers about the differences between home and road teams. He notes that not only do home teams accumulate more shots on goal, but also that they have a higher Finish Rate (i.e. they convert a higher percentage of their shots on goal) and wonders why that would be the case. Fortunately, I think I have an answer for him.

First of all, let’s ask the important question: why should being the away team make any difference in the outcome of a game? The field, the ball, the rules, the play; they’re all the same. What is it about playing away from home that makes any difference at all? There’s the comfort factor obviously. You are certainly more apt to be ready for the game if you wake up in your own bed and can follow your usual routine. Traveling can also fatigue the body, especially if it is a long trip. There may be certain details about the field of which you are unaware or can’t take advantage (ever notice how all of those ballboys at Stoke have towels to wipe off the ball for throw-ins just to help Rory Delap?). But the main difference is you don’t have the support of the fans.

What kind of impact can the fans have on a team’s ability to convert their chances? If you answered “negligible”, I think you’d probably be correct. However, fans do have a significant impact on the referee and how he makes decisions. In every sport, referees tend to give more calls to the home team and soccer is no exception. Fair enough, but what does this have to do with improving the home team’s Finish Rate? Simple. The refs not only award more free kicks for the home side, they also award more penalties.

As we know, penalties have the highest Finish Rate of any type of shot on goal; 80% of penalties that result in shots on goal go in the net. If a ref awards only a few more penalties to home teams relative to away teams, home teams will get a relatively massive boost to their Finish Rate because it is so easy to take those opportunities. It follows then that a team playing at home would post a higher Finish Rate than they would on the road. So far this year, the evidence has backed this hypothesis. Including penalties, teams have a Finish Rate of 31.14% at home, compared to 30.45% in all games. If we take out penalties, teams have a Finish Rate of 27.84% at home, below the 28.12% they average in all games. It seems that penalties are indeed what inflates the Finish Rate of home teams.

Though there may be differences in approach that make certain teams have a better Finish Rate at home or on the road, league-wide that doesn’t seem to be the case. Unfortunately, what seemed to be an intriguing difference between a team’s play on the road and at home is no more than a function of the referee.

No comments:

Post a Comment