Sometimes, we collectively overthink this stuff and sometimes we underthink it.
To win (besides, at times, having some good fortune) the following are all important ingredients (not in order of priority): athleticism, talent, skill, work ethic, court intelligence. Obviously, these categories are not mutually exclusive and obviously (to me) you don't get to the level of a Federer, Nadal or Djokovic without scoring very high in every area.
If you see one as being so much more athletic or talented or skilled, or having so much more court intelligence or work ethic than the others, I don't see it.
Let's not overthink this, either. Roger is oozing with talent, but he still scores high in every other area. Rafa is an amazing athlete with great mental toughness, and is also phenomenally talented. Novak is incredibly skilled with a great on-court mentality (yes, he has a temper, but that's beside the point) - and he's incredibly talented.
But, we tend to categorize players in all sports as the athletic one or the skilled one, or the hard worker, etc. And sometimes, we miss the big picture.
I won't unlock the riddle of Kyrgios, but in which categories does he rank high? Yes, he's talented, and fairly athletic. He has power and touch and anticipation. But how skilled is he at developing good strokes? How is his work ethic and his mentality on court?