If you told someone Mandzukic would score a bicycle kick in a CL final they would tell you you're insane. Not saying we don't need top quality players, but not every player has to be a household name.
Just to be clear, why do you use Juventus and not Real Madrid as an example, Mandzukic isn't a lesser player than Casemiro?
My point is the following, Juventus are full of world class players like Real Madrid, they are not the example of the system being above individual talent or "names" like some will say.