When will MLS be a top league in the world? When possession matters

MLS Commissioner Don Garber is on a journey to make his league one of the best in the world by 2022. This leaves two big questions to be wrestled with over the next six years. The first is how exactly will Garber make that happen in such a relatively short period of time? The second is how will the world know when MLS has truly arrived? An answer to the first question is a plan that only the head office and perhaps owners really know, but the answer to the second question is something that the soccer world should be able to observe. Ranking leagues on quality is a much-debated and unending discussion but perhaps there are some observable outcomes that will help.

As far as Major League Soccer is concerned, some believe that consistently winning the CONCACAF Champions League is a prerequisite to even start this conversation. Some say the league will simply need to afford salaries on par with the top leagues and compete for the best talent. But I'll posit another way the world will know: when possession matters.

In the best leagues in the world, which team has more possession actually matters from a perspective of predicting who is likely to win. In MLS, and in leagues of similar quality, it matters much less. Last year in MLS play, home teams won the game outright 53% of the time. When those home teams held a possession advantage, that number was 52%. Possession didn't matter.

Much has been written about the fact that possession is a high-profile statistic that is low on value, especially when looking at single-game results. But over the course of a season in top leagues, teams that maintain more possession do finish higher in their table. Here is a chart of what are generally considered the five best leagues in Europe and how possession relates to points per game. The data is compiled from Whoscored from the last two complete seasons combined.

The R squared figure on the chart means that 57% of the variance in the league table can be described by looking at possession. The one league that sits apart from the rest in this group is Spain's La Liga, which has the weakest correlation of the group. This departure is primarily due to the recent thrilling runs by Atletico Madrid, a club that generally splits possession 50/50 with their opponents.

Whoscored also tracks possession statistics for a few other leagues that are considered a step below those top five leagues. The next group looks at Brazil's Serie A, the Championship in England, the Eredivisie in the Netherlands, and the Russian Premier League.

There is a similar trend but the relationship is not as strong; most notably the Championship has a less steep curve slope than the other leagues. Note the R squared in that chart shows that possession is less predictive of points in these leagues.

Looking at MLS and Australia's A-League, with data from ALeagueStats.com, we see a dramatic shift in the importance of possession.

The relationship looks noticeably weaker and the R squared value shows that possession predicts very little of the table results. There is still a positive relationship however.

Why are we seeing this? What does possession get you in one league that it fails to give in another? Logically possession is a benefit because it increases the likelihood one team will shoot more often while reducing the chance for the opponent to shoot. Possession should lead to a better shot differential and a better shot differential over time should lead to an advantage in goals. Looking at these same league groupings, it's evident that possession translates into a shot taking advantages for better leagues and fails to do so in others.

Here is possession against shot differential per game over the past two full seasons in the top five leagues.

Here is possession against shot differential per game over the past two full seasons in the Brasileirao, Eredivisie, Russian Premier League and the English Championship.

Here is the data for MLS and the A League.

In Major League Soccer and A-League, a possession advantage doesn't translate efficiently into a shot advantage. It appears in better leagues that possession does yield a shot advantage. To complete the circle, and cut to the chase, here are the correlations between shot differential and points for eleven leagues.

The better the league is considered the more shot differential translates to a positive effect in the final standings.

In the interest of keeping score, the better the league, the more possession translates into shot differential and the more shot differential translates into wins. Is the data simply revealing the obvious, that the better the players, the more efficient they are at creating advantages and producing wins?

If the soccer market is efficient at recognizing and paying for talent, and given the financial means of the market that's a safe assumption to make, then salaries paid should be a reasonably good proxy for talent. Here is a plot of the average league salary, taken from a Sportsmail study in 2014, against the correlation between possession and points.

The better the talent the more possession matters. Perhaps we could have started this whole conversation with that chart alone as it provides a more concise view. Yet I imagine some of you are still wondering if there's another reason for this difference in the importance of possession between leagues. There are two more angles worth exploring and the first is the fact that both the A-League in Australia and MLS have a salary cap system, whereas the other leagues in this analysis do not. Could it be that the parity created by a salary-constrained system is what neutralizes the talent within the league and therefore makes possession less important? It's certainly possible.

But the salary cap doesn't really flatten the salary distribution in MLS like most believe. Here is a chart of the English Premier League's distribution of wages by club against the distribution in MLS for just one season.

The Designated Player rule in MLS allows the salary distribution across teams to look like a league without a cap restriction. In effect the Designated Player rules creates more of a free market system in MLS than one would think. Although it is probably true that the distribution of those salaries is likely different and that could have an effect. EPL salaries are not available at that level however.

The other aspect of MLS that could keep ball control from its normal effectiveness is the playoff system. With twelve teams getting a playoff spot there might be less incentive to build a possession-based team if a different system could still get a team to the playoffs. If a coach felt his team could not be successfully consistent seeking possession, then he may commit the team to a more defensive style and there would still be a chance for playoffs and a run at the MLS Cup.

Right now in MLS teams enjoy success playing a variety of styles that value possession differently. The top three teams in the Western Conference last season - FC Dallas, Vancouver Whitecaps and Portland Timbers - all held less than 50% of the possession for the season. In the Eastern Conference the top two teams - the New York Red Bulls and Columbus Crew - ranked first and second in possession in the league, respectively. But as the league improves Don Garber and the fans will see that teams with more possession perform best over time. And when that happens, perhaps MLS will have a claim to be hanging with the big boys.

You can look at any of the leagues in this analysis by selecting the league in the upper left hand corner of the chart.

Data for this article was sourced from whoscored.com, aleaguestats.com, americansocceranalysis.com, and mlspu.com.

Special thanks to aleaguestats.com which collected additional data to help with this analysis