The Impact of MLS expansion on playoff qualification

In an earlier post I commented on the points and goals it would take to secure at least 8th place in the 2010 MLS table - the cutoff for the playoffs. I then wondered how those numbers would be affected with the addition of Vancouver and Portland in 2011 and Montreal in 2012. Luckily the response variable I used in the regression was generic:

-ln[p/(number of teams - p)]

Therefore, I can simply plug in the number of teams for the next couple of seasons, determine the response value that correlates to p=8 for each number of teams, and create the same 95% PI and CI values for each season. Figure 1 shows the results of that analysis up to the 20 teams everyone suspects is MLS's ultimate goal. I skipped the scenario for 17 teams given that the league will jump from 16 to 18 teams in 2011.

Figure 1: Goal differential and points required to make MLS playoffs based upon 16-20 teams (click to enlarge)

The net effect of adding each new team is to add one more goal and one more point to the minimum required to qualify for the playoffs.

There are a few assumptions made in this analysis. First, I assume that team performance holds to the historical average from 2005 through 2009. I will attempt to mitigate the impact of this assumption by updating the regression data set at the end of each season with the previous season's data. Second, it doesn't account fully for the additional points that would be available to a 18 to 20 team league running a fully balanced schedule. The most games any team played in the 2005-2009 time frame was 32 in the 2005 and 2006 seasons. If MLS were to keep the balanced schedule from 2010 in 2011, the league would jump to 34 games which means 6 extra points available to each time beyond the maximum available in my regression model to date. One might expect a shift upwards in the points required to finish eighth once teams are added.

It will be interesting to see how well the regression prediction plays out this season with the addition of the 16th team, and into the next two seasons as three more teams are added.