If you talk about individuals and start comparing it will not answer the question. So far i seen CT, Maddison, Bigi and Vardy's name mentioned on here, all are different all have different attritbutes. And in the end all will find the natural level that they can compete in. Players who have stepped up that have limited attributes will fall to the correct level, not because they are bad but because other in the squad members in the same position have more attributes.
And for me its as simple as that, form, injuries and confidence have not made CT stop in levels, his attributes have. He will make a good living out of the game and during parts of his career will find the right home and hit form, but his level is what it is. I wish him well just dont see him going much higher than he currently plays, if he does good luck to him.