In a grand scheme of things that doesn't matter, in other eras too his slam count would be same, he definetly cannot beat Federer in 00s if he were of that gen, he wont be winning french, so what happens to his slam tally ? If in the 90s then he definetly isn't beating Sampras and Agassi, then what happens to his grand slam tally ? Being 3rd wheel never helps in a grand scheme of things, it is just useful to say that hey I reached semis and then lost, some fanboys will say that he could have done better in other eras, thats it but real tennis fans know that his tally would be same in every era.
A real slam winner in any era has to beat the TOP CHAMP, if you need to win WImbledon/USO in the 90s then you have to beat Sampras, if you can beat Sampras (Like Krajicek did) then beating Agassi/Henman/Rafter etc etc would not be an issue, so the question of many players peaking does not affect you if you can beat the Alpha.
Safin beat Federer in the semis of the AO, then was it a issue for him that Hewitt was in the finals ? No because he obv beat a superior player.
Stanimal beat Djokovic in the Qfs of the AO, so was it an issue for him to beat Nadal in the final ??? no ....
So Andy never was in a position to beat the greatest player on that turf, so the other 2 guys being there has no bearing on his greatness