Last update on Saturday April 16, 2016
Because it's like comparing apples and oranges : singles and doubles are different. Being good in doubles does not necessarily mean that you are good in singles and the reverse is also true. This is a rating system to rate individual players.
Another reason is that in para table tennis, the difference in ability between 2 players can be significant especially when several classes are combined. This is even more obvious when looking at standing players where quick moves are necessary to hit the ball alternately.
Let's take the example of a class 10 player playing with a class 7 partner playing against another pair composed of 2 class 8 players. Now, let's say the class 10 player runs quickly enough to compensate his/her partner's more limited motion and they win, how should their rating evolve? Is it fair to say that the class 7 should half of the points or should he get less but then by how much?
This could be the case with the previous ranking system where a strong player could get points for winning against a weaker one. With the rating system, this is no longer the case.
Let me take a real example from Lignano 2011 in TM9: UKR vs. ESP. The Ukrainian team was much stronger than the Spanish team, a difference more than 500 points in ratings.
The results were as follows based on the rating system: