As you say, logically it should be there, but I simply do not see it. I know JJ is getting to number 1 without even being to a GS final, but I can only recall Marcelo Rios and Ivan Lendl becoming number 1 without winning a GS (Lendl of course did it afterwards). With today's ranking system and depth in the men's tour, I think it would be impossible to reach number 1 without winning slams.