2012 MLS Regular Season Home Field Advantage

Today, we are all focused on the second leg of D.C. United's Conference Semifinal series against the New York Red Bulls. The Black and Red United community has done a great job breaking down the two opponents in this game, and there is more to come before Wednesday night's kickoff. With that said, there is another opponent D.C. United will be facing in the second leg, an opponent D.C. United wasn't expecting to face on this specific night. That opponent is the home field advantage New York will enjoy in the second leg, and it's the same silent opponent the Red Bulls faced at RFK on Saturday night.

This post isn't a complaint about the swapping of home dates that occurred last week in this playoff series. Major League Soccer and the two clubs did what had to be done in the face of one of the worst natural disasters to hit the northeast in recent memory. All in all, it was ultimately handled well. Rather, let's take a look at home field advantage in MLS and how it compares to six other prominent soccer leagues around the world as well as the four other major North American sports leagues.

I'll build the case below, but for those of you who want the bottom line (the BLUF--bottom line up front), during the 2012 regular season, MLS teams won a greater percentage of home games than teams in any of the global soccer leagues that have better annual attendance than MLS. Additionally, the spread between the winning percentage of teams at home compared to their road winning percentage is greater in MLS than in any of the other leagues reviewed. This final statistic also holds true when comparing MLS to the other major North American sports leagues.

We'll start by comparing MLS to the following soccer leagues: Bundesliga (Germany), English Premier League (England), La Liga (Spain), Serie A (Italy), Primera Division (Argentina), and Liga MX (Mexico). Again, these are the six soccer leagues in the world whose average attendance is greater than MLS's. For these leagues, I've used statistics from the most recently completed league season (for the Primera Division and Liga MX, I've combined the results of Clausura 2012 and Apertura 2011 for each league to get a full season's worth of games).

So, how do you measure home field advantage? Let's look at a few different ways.

1. Average home winning percentage. One way to measure home field advantage is to look at the average home winning percentage of teams in each league across an entire season.

From this table, it is clear home teams in MLS not only enjoy a greater home field winning percentage than the other global soccer leagues (and it's a significant difference in some cases), but MLS home teams also lose less often and draw less often than in the other leagues.

For additional comparison, the table below has the overall winning, losing, and draw percentages for all teams in these leagues, irrespective of whether they are playing at home or on the road, across an entire season. When compared to the table above, this helps to demonstrate how much better teams perform when playing at home.

2. Percentage of games in which home teams get a result (win or draw). What if we add the home winning percentage and the home draw percentage to see how often the average home team in each league gets a result?

From the table, we see that the average MLS home team is more likely to get a result at home than home teams in other global soccer leagues. Further, if we compare this "Home Win or Draw %" against the "Overall Win or Draw %" (which includes both home and road games), we find MLS still has the largest home field advantage.

3. Difference between home winning percentage and away winning percentage. For me, this is the best statistic to measure the overall home field advantage enjoyed in each league. Basically, how often does the average team in each league win at home compared to how often the average team wins on the road?

In a staggering stat, MLS teams on average win twice as often at home as they do on the road! While La Liga comes close to replicating this stat (but falls just short), the MLS home field winning advantage is significantly greater than many of the other global soccer leagues (more than twice greater than the Argentinian Primera Division and Liga MX, and almost twice greater than the EPL).

4. How does MLS home field advantage compare to home field advantage in the other major North American sports leagues? First, let's look at the National Football League, Major League Baseball, and the National Basketball Association. These leagues are different than the soccer leagues above because every game has a winner and loser (whereas in soccer, a draw is a possibility). Yes, it is true that a regular season game can end in a tie in the NFL, but it is so exceedingly rare (it has only happened twice since 2002, and it did not happen in 2011) that it doesn't factor into this comparison. This means that the average team in these leagues wins exactly 50% of its games and loses exactly 50% (as compared to MLS which has an overall winning percentage of 38.08%, losing percentage of 38.08%, and a draw percentage of 23.84%). While this makes the average home winning percentage for the other North American leagues greater than MLS's average home winning percentage, when compared to their average away winning percentage, the resulting home field advantage is still significantly greater in MLS (four times greater than in MLB).

The National Hockey League has its own unique competitive system that is a blend of the system used in soccer leagues and the system used in the other North American sports. First, while NHL has an overtime system that ensures games do not end in a draw, the NHL awards 1 point to a team that loses in OT (approximating a draw in soccer). Second, however, a team that wins in OT gets full credit for a win (2 points). This means every game has a winner (like the NFL, MLB, and NBA), but, like soccer, every game does not have an outright loser that doesn't get any points.

Looking at the most recently completed regular season, the home field winning percentage is higher in the NHL than MLS's home field winning percentage. The overall advantage of playing at home for MLS teams, however, is more than twice that of the NHL.

Lastly, if we compare how often teams win or draw (approximated by an OT loss in the NHL) at home in these two leagues, it is greater for MLS. When compared to their overall likelihood of getting a result of some type, irrespective of playing at home or on the road, MLS teams have an advantage at home that is more than twice as great as teams in the NHL.

* For the NHL, a "draw" is actually an overtime loss for which 1 point is awarded.

Conclusion:

In the 2012 regular season, home field advantage in MLS was real, and it was stronger than in the other major soccer leagues around the world. It was also stronger than in the other major North American sports leagues.

The MLS playoffs, however, have different dynamics with playoff seedings and two-game series based on aggregate goals (except for the two play-in games). It remains to be seen whether home field advantage will be as dominant in the playoffs as it was in the regular season. So far this postseason, with six matches played, home teams are 2-2-2.

D.C. United will have to face both the New York Red Bulls and their home field advantage on Wednesday night (and the weather). But, let's not lose sight that United continues to ride an eight-game unbeaten streak that is now tied for the third longest such streak in the league during the 2012 season. This team has found a way to grind out results for almost two months now, and who's to say they won't defy the regular season stats and do it again?

What do you think about the home field advantage in MLS? Why is it so strong? Does it say anything about D.C. United's match on Wednesday night?

If you like numbers, download the spreadsheet that contains the source data for this post (MLS Home Field Advantage) and leave a comment with your corrections/suggestions/questions.