If this formula work at grass yeah, should be also on clay.
I agree with Sophocles, players like Roddick don't deserve too good seeding if they don't show nothing on clay. All the same how is his draw, he never win more than two matches. His best result at RG is R4 even so he is former no1.
And this Bellucci - Gasquet R3 match was shame even so both of them played semifinal in this year on clay.
Anyway I would use it at all Grand Slam or nowhere.