How does rating difference relate to PPG?
Points-per-game (PPG) is a measure of the relative strength of two players. Play a series of games; take your net points won or lost; and divide by the number of games you played. That’s your PPG versus that opponent. Since both PPG and rating difference are measures of relative ability, you might expect there to be a relationship between the two. David Montgomery has studied this (see this post). He estimates that a win rate of 0.10 ppg corresponds to a rating difference of 40-50 points.
