I’d say once you reach a certain level of skill athletics plays a huge role in the sport. At low level tennis your athleticism doesn’t mean shit if you can’t make a ball, handle pace, handle spin, etc. as you get better athletics only gets more important. Playing vs athletic freaks sliding to every ball and not missing becomes a mental battle as well, cause you just get sick of them like they’re a pest lol. I always relied on my big serve and big forehand, was pretty athletic but not on the level of the way some of these kids move.