It's built into the definition of the rating. A 200 point difference in rating always means that there's a 75% expected chance of the higher ELO winning. In les

It's built into the definition of the rating. A 200 point difference in rating always means that there's a 75% expected chance of the higher ELO winning. In less fluid arenas, the actual ratings can diverge from ideal ratings but there's enough matchups in chess that this isn't a huge concern.