(7405) Federer Minimum
 Nadal Maximum
 Djokovic Maximum
 Del Potro Maximum
 Murray Maximum
Roger only needs 455 points in the clay season to make it impossible for Nadal to pass him.
How do you get those figures for Nadal - did you forget he lost at Roland Garros in the fourth round last year? I make his maximum 9280 after the French, and he can only gain in Paris and Madrid. With Federer's minimum 7315 (my calc), that's still an awful lot of work for Roger to do.
Also, my numbers show Del Potro at 10045 max, and Djokovic 11070; Murray's max is lower - 8935. It's far from done.
Edit: Murray max now 9935 with the Monte Carlo wildcard