He does not have neither the physical nor the mental strength to become a big player.
As for the bolded part, I am not sure. During matches, I think he is one of the toughest guys out there, mentally wise (or the craziest, but the outcome is equivalent). The name of the game is "do not get tight on big points". And in this prospect Kyrgios is hands down one of the best guys on tour.
Maybe he does not have the focus necessary for hard training (but I honestly don't buy this "I don't like to train" that easily), or, even harder, the focus needed to correct and improve the aspects of his game that need real improvement. I understand what people say when call him "talented" (even if my definition of talent is different), but even taking this into account, he really needs much better ground strokes if he wants to get higher rankings. What he has in his bag right now is not enough, maybe only for an occasional good result on a fast surface. So far, results wise, he has not been spectacular.
But time is not running out just yet... even if you assume that he won't be a late bloomer like so many have been lately, he still has almost two years to become 25 years old (if I am not mistaken).
BTW, after, what, around 35 years, I just won a tennis tournament!
