The difference in ratings means the expected result of a personal meeting.
Rt (A) – Rt (B) = 1000 * (Goals scored – Goals conceded) / (goals scored + Missed goals)
1000 – scale factor. If the difference in the ratings of the two teams is more than 1000 points, then in their personal meeting will only score one of them.
The difficulty is that all sports are different in performance and even in one sport there is always a lot of polarity in performance. Strictly speaking, we do not know with what effectiveness the teams will play.
In this situation, we display the rating on the total amount of goals scored and conceded, equal to 10.

Football. If
Rt (A) – Rt (B) = 200, this is the 2 advantage of the ball for a personal meeting, where 10 goals are scored.
Rt (A) – Rt (B) = 200, the score of the game is 6: 4
However, in football they really score 3 goals. Then the actually expected account will be three times less
Rt (A) -Rt (B) = 200, the score of the game is 2.0: 1.3

Basketball. If
Rt (A) – Rt (B) = 200, this is the 2 advantage of the ball for a personal meeting, where 10 goals are scored.
Rt (A) – Rt (B) = 200, the score of the game is 6: 4
However, in basketball, actually gaining 150-200 points. Then the actually expected account will be 15-20 times larger. If there are 150 points, then
Rt (A) – Rt (B) = 200, the score of the game is 90:60