Shaping Form

One of the problems I have with the Elo rating system is that winning is everything. Your points are at stake, and if you lose, you lose them. It doesn't matter who you lose to. If you're say Accrington Stanley and you lose to Manchester United your rating diminishes just the same as if you'd lost to Rochdale. If you win, then who you beat matters. It doesn't seem right that if you lose, the strength of your opponent doesn't matter.

The other thing I have been pondering for a couple of days, is weighting a teams 'performance' rating. This idea was triggered by Peter Nordsted's comment that he looks at how "teams have fared in recent matches against opposition of a similar quality". While this would add another level of complexity to an already complex enough equation, it did get me thinking that it would be relatively easy to adjust a team's performance rating to take into consideration the opponent's strength. Clearly, it is far better for a team to have 10 corners and 20 shots on-target away to Arsenal than at home to Darlington.

Back to the Elo ratings for a moment, and the best predictor right now is not the rating itself, but the relative difference in ratings for the two teams over the past six games. For example on Saturday Birmingham City played Bolton Wanderers. Over the previous six games, Birmingham had gone down by 123 points, whereas Bolton had improved by 3 points. Although both home and away selections are in profit, the system is especially accurate if the form team is at home with 22 winners from 30, but 4 of those losers were on opening day when the form dated back to last season, and should probably be ignored.

Odds-on favourites in the Premier League are also having a good run right now. Since August 24th, only 1 (Chelsea at Wigan) has failed to win. 22 winners from 23 selections. And still the draws are nowhere to be seen.