Past performance is no guarentee of furture results

So during a discussion of Elo ranking for MLS teams (specifically the rankings that Alan is doing over at When Stats and Soccer Unite) over on BigSoccer it was brought up that carrying over rankings form previous seasons may not be appropriate, as in MLS past season performance has almost no correlation to the next season. It seemed a little odd, so I decided to check it out. Using final positions from 2007-2012 (through 8 weeks) I pulled out the linear correlation coefficient from each set. Turns out, it's more or less true. With an odd exception of 2009 results and the 2010 season there's very little correlation in past season performance vs. performance the following season.

	2007-2008	2008-2009	2009-2010	2010-2011	2011-2012
R	0.324	0.536	0.026	0.703	0.292
R^2	0.105	0.287	0.001	0.494	0.085

I also broke out all the results for those years and did an overall correlation. For all seasons from 2007 - 2012, the numbers were :

R	0.3951
R^2	0.1561

Basically, it seems like, in very broad and general terms, not to mention horrible missuse of statistics, results from the previous season only equate to about 16% of a teams performance in the following year. I'm not sure what happened in 2010-2011, but it was suggested that as franchises settle out and MLS becomes more stable teams will gain more identity. This may be true, but I think in a salary capped league, even with DP exceptions, we might see a lot more parity like this. Which I would argue is a good thing. Don't get me wrong, I love watching European juggernaut clubs fell lesser opponents and go at each other head to head every so often, but in the end, having only 10-20% of the teams in a league really contending for a title each year is a bit boring. I think MLS is doing it right, and if low correlation from season to season in performance is one of the consequences, I say bring it on.

Also, I went to the reserve game tonight. Was a lot of fun, I'd never been out there before. Great night for it and it really made me appreciate the speed that professionals play the game at, not to mention the amount of on-field communicaiton happening. I think it really opened my wifes eyes up as well.

Here's a picture. I'm mostly just putting it here so the preview photo isn't the same SKC icon it is on every single post. Also to break up the blogs wall-o-text feel.