Even after withdrawal from Istanbul Maria has remained the most efficient player on WTA Tours.
As of October 31, 2011 the Efficiency Ratio is as follows: Sharapova - 434, Kvitova - 388, Wozniacki - 340, Li - 318, Azarenka - 311, Stosur - 266, Radvanska - 263, Petkovic- 254, - Zvonareva - 247, Williams - 245, Bartoli - 168.
Philli, that means a ratio between Rank Points and the number of Tours (http://www.wtatennis.com...0,,12781~0~1~100,00.html). To win a point Maria needs much less matches than any other top 10 player (plus Williams).
I calculate the efficiency ratio by dividing Rank Points by the number of Tours and then sort it in decending order. These figures are available from http://www.wtatennis.com...0,,12781~0~1~100,00.html (WTA | Rankings | Rankings – Singles). A more presize measure of productivity is Rank Points divided by the number of matches (not Tours), but I am not willing to go that far.