Elo rating vs official ranking: what's the difference?
An official ranking and our Elo rating look similar but answer different questions. Here is why we predict with Elo.
What an official ranking is
An official ranking is usually a points table: players earn points for results over a season and are ordered by total. It rewards activity and tournament prestige, and it can lag real form because points are shed slowly.
What an Elo rating is
An Elo rating estimates current strength directly. It moves after every match based on the result and the opponent's strength, so it tracks form quickly and is built specifically to produce a win probability between any two players.
Why we predict with Elo
Rankings tell you who has earned the most over a period; Elo tells you who is likely to win tonight. For predictions you want the second. Elo also converts cleanly to a calibrated probability — a ranking position does not.
That said, the two usually agree at the top. Where they differ, it is often Elo catching a rising or fading player before the ranking does.