So say Federer won Hamburg, he would not gain the 500 points until October?
He would gain the 500, but the 90 he got from Rotterdam would not count anymore (they do today) so his net plus would be 410. The zero-pointer cannot be replaced, but all the other ones can. So there's not more than 90 points in it for him now, but last year under similar circumstances he'd forgo 500 points as he had 500 from both Basel, Marseille and Dubai and the same zero-pointer from Tokyo. It other words, if he'd added Hamburg to his schedule last year even a win would - temporarily - have added nothing to his point total. He would have got those 500 points in October, though.