Because it's more of a myth than a fact. And I find it hard that anyone can agree with you saying that he's out of his depth and useless when he's constantly producing goals or assist when playing on the left wing. It just doesn't make sense to me. He was a disappointment on the left in 15/16 and didn't play much on the left last year iirc. But this year he's been good when played there. He maybe doesn't look as threatening or good compared to when he plays on the right. But he still produces excellent number in terms of goals and assist so he's obviously doing something(s) right.