In fairness, Phil Jones' career was ruined by injury, he was very promising back in the day.
You're comparing him to 4 of the best strikers in the world who have played nowhere but through the centre their entire careers, rather than being shunted out wide. Let's be realistic here, he obviously won't be spending as much time in the box playing as a conventional winger under Mourinho, rather than a centre forward in attacking teams.
He does have to improve, but to say he has no chance of becoming world class is nonsensical, he has all the physical and technical tools and is just entering the point in his career when consistency usually start to develop. He's still 23, by the premier league's definition, he is still a young player.