First of all, grades are nothing. It only means that a guy has played a lot matches with the same player, so don't be in subjection against these users.
Then, maybe they seem faster cause they can use better the shots. Use R1 to reach the ball, but be careful to release the button in time, otherwise the player will go toward the net.
And of course u can use control shots, to counter the power shots of the opponent. Of course it's not easy to master them, but they are a good help during tough matches.
And try to vary your tactics. A lot of WT players do the same game all the time: you change something to get them in trouble, but they dont seem to realize it, and keep playing the same way...and lose

PS I'm telling you all these things cause we will still have to wait a looong time before TS5 to be released.