Because he's pretty much the tits in the midfield. Right now he's one of the best left wingers in the world and he's just getting started. He's the new prototypical box to box midfielder and I'm not even sure that he's even in his "best" position. I think one day he'll move inside and adopt the number 10 where his potential is scary good.
When Zidane says you have a chance to be one of the greatest French players of all time, you're pretty good. He still does disappear at times for long stretches so I think he could be more assertive at times but that boy real, real good.