ELO ratings level out eventually for a given pool of opponents. If a player already wins every game against all available opponents, there's no evidence that ca

ELO ratings level out eventually for a given pool of opponents. If a player already wins every game against all available opponents, there's no evidence that can tell you if they suddenly got twice as good. If tracking improvements past the state of the art is important I think they'd have to freeze the algorithm every 400 ELO or so and rate the improved versions against the last snapshot. (Doesn't really apply to the stockfish case, but it does to the other two games.)