How we turn betting odds into team strength
How good is a football team? Most people look at the league table. But the table is about results, and results are noisy. A team can play well and lose to a lucky goal, or play badly and still win. It takes a long time for that luck to even out.
Expected goals (xG) helps. Instead of counting goals, it counts the quality of the chances a team made and gave away. That is a better signal. But xG only sees the match. It does not know that the best striker was injured, that the coach rested half the team, or that the other side had nothing to play for.
The odds already know
Betting odds see all of that. Before a match, lots of people — and some very sharp betting firms — put real money on the result. To win, they have to guess the true strength of each team, right now. Injuries, tired legs, motivation, the weather: anything that matters gets built into the price, because ignoring it loses money.
The closing odds, just before kick-off, are the sharpest guess of all. By then every bit of news is in. Studies keep showing the same thing: these odds are very hard to beat. They are the best public prediction we have for a match. A result is one noisy sample of that prediction. xG is a better sample. The odds are the whole estimate.
From odds to strength
So we start from the odds, not the results. For each match we take the closing odds and turn them back into a simple number: how many goals each team was expected to score. That is the market's verdict on that game.
Do this for every match and a pattern appears. A team the market keeps expecting to outscore strong opponents is strong. We use this to give each team an attack score and a defence score, after adjusting for who they played. Add them up and you get one strength rating for every club, updated every day.
That is the whole idea. We do not try to beat the market — almost no one does. We let it do the hard work it is already great at, and read team strength out of it.
See the current numbers on the league tables and the experimental global ladder.