In a press conference on Sunday, Roger Federer commented on how different grass is as a surface in tennis compared to hard or clay. The Swiss player said: "One good shot or one good return really makes a difference on this surface, so in my mind it comes very naturally to look at how to finish the points at the net, how I can develop a point.
Naturally, I think slice is always a good shot on grass as it stakes a little bit and the opponent has not only to hit the ball in a more difficult situation, but he also has to comeback and give a court position which is not something you want to do on the grass, and then it's this constant burst of energy you need to have on this surface, because if you are not having it or you are not willing to put in that effort and you are just gonna be a little bit lazy about it, you are gonna pay the price for it.
Whereas on clay if you are playing from the baseline you can get in a very natural good rhythm because you always have a little bit of time and that's why guys return from the back, especially the best ones, because you really get comfortable back there but on grass you cannot really do that, so you have to stay close to the opponent, to make a difference otherwise you are in too much trouble, so i like that about grass especially right off the back of the clay-court season, it's a big change if we saw at Thiem, Rafa and Stan, how they are returning. How could do they do that on the grass? That changes everything, also their game as well."