Because the players in the nineties all specialized in returning serve
here are the players who won slams on fast courts in the 90s (i.e wimbledon and us open)
sampras, agassi, rafter, edberg, krajicek, and stich
so you have three all around players, an offensive baseliner, and two serve and volleyers, if you wanna put terms on them
as history has shown, sampras and agassi were more than good enough at returning serve. krajicek got hot for two weeks and stich retired early
that leaves rafter and edberg. tsonga is no where near edberg's level. rafter's...well, he has a better serve, and a better forehand, rafter with better volleys. return of serve...
the point is that tsonga's serve and volleys make him stand out in this era. in an actual era of those, he would have no chance
This court was pretty fast compared with the rest of the tour, and there was no reason for Tsonga to throw in the towel after the call didn't go his way.
while it's true that toyko is fast, comparatively...the fact is that tsonga does not have the belief to beat djokovic
he had match points, on his worst surface, at his worst slam. didn't take them. does not have the belief in the big moments