Wednesday, October 28, 2009

MLS End of Regular Season Rankings

The season has wrapped up and the playoffs begin on Thursday. I'll shortly post an article with playoff discussion. I wanted to separate the ranking discussion because it turned out to be a lot longer than I thought it would be.

End-of-Season Rankings

O Rank - goal-scoring rank
D Rank - goal-preventing rank
EGD - expected goal difference if each team played two matches against every other team at level shown by season results

A feature of my rankings is that at the end of the season for most leagues the rankings converge to goal differential. They don't for the MLS and Scottish leagues due to the unbalanced schedule. Each team plays every other team twice with two additional matches against a conference opponent. They stay pretty close, but teams with harder or easier opponents those extra two games will have their expected goal differential adjust based on how hard they were. For example, Houston and Columbus finished even on goal differential but Houston's extra games were against tougher opponents - Salt Lake and Dallas compared to Chicago and Toronto.

For a comparison to other rankings, here are Elo ratings. There is an explanation link near the top of that page. Elo ratings are commonly used for chess. There is a formula that gives or takes away points based on the result, including the score, of each individual match. The Elo formula emphasizes the match result which I ignore. I just take goals scored and allowed into account giving no extra bonus for winning or penalty for losing. The other big difference between that and what I have here is that there is some carryover from last year in those ELO ratings and I just started from scratch at the beginning of this season. To be honest, I think including previous results is probably better for stating which teams are the best. It's one of many things I plan to work on in the future as I'm not sure how to best use old results.

For a subjective rankings, check out Soccernet's Power Rankings. They "consist of a consolidation of votes from Jeff Carlisle, Jen Chang, Steve Davis, Frank Dell'Apa, Kristian Dyer, Ives Galarcep, Allen Hopkins and Andrew Hush." In my view they seriously overrate New England and Chivas while underrating Salt Lake and Colorado. This doesn't surprise me as these were teams that over or underperformed in close matches, which I've shown is mostly (and probably all) luck.

Looking at the season as a whole, I think it's fair to say that Houston and Columbus are the top two teams in the league. I think you can argue either way which of the two is better. Columbus won the Supporters Shield given to the team with the most points in league play. Houston finished just one point back and played a slightly tougher schedule. Really there's not much separating them and a bounce here or there could have flipped things. The Galaxy finished the league even on points with Houston but again I think this was because they had good luck in close games.

No comments:

Post a Comment