Since they derive from the expected goals, they represent the ability to create better scoring opportunities and to concede the worst.

Consequently, the actual points indeed tell us if the team has overperformed or underperformed and it is equally true that they tell us about the quality of the players involved.

I mean, between two teams with the same expected points, there will be one with more or less points than the other because the quality of his players is higher or lower than the average.