The best always make it look easy.
As quick as he is, his relaxed manner between serves, which can appear to be almost casual, and the fact that he displays very little emotion (and I've never seen him express anger) has led some to comment that his game is mechanical, ignoring, it seems, the often referred to as balletic movements that he manifests in his incredible athleticism, all while conserving energy which other players may squander with fits of anger or emotion - the guy is poetry in motion!
He always plays hard enough to try to avoid, to paraphrase him, "stupid five set matches".
Stirling Moss drew similar comments from some who watched races wherein drivers slipped and slid, sawing steering wheels back and forth with great vigor, while Moss motored calmly on by them, as if on a Sunday drive.
Afterthought - in boxing, a knockout is what counts; not how FAR out
.