To me it looks like most top50 players now have very good modern strokes. a lot of them can hit 90 mph FHs and hit very hard and consistent. out of the middle of the court (or one of the corners when they are sitting on one corner in the CC rally) they hit very well but once they are stretched out far usually their shots become a lot weaker especially at the BH side (most can hit a FH on the run but fewer can do the same on the BH). the big 4 on the other hand can still hit very penetrating when they are stretched out to the side. the other players do reach those balls too but they have to play it more defensive. this becomes obvious if guys like tsonga play Novak or fed. tsonga can hit those 100 mph FHs (certainly harder than nole) but against those players he is still often in defense). ferrer is a little in between. he is a little better out of the corners than Tsonga and the other hard hitters (he usually beats those big hitters pretty badly too) but not as good as the top4. so why are the big 4 (especially nole is very good in this) so much better out of the corners, especially on the BH side? and why can't the other hitters duplicate that? in a normal CC rally all the players look relatively equal but this changes if a player has to stretch out.