Mata has played right wing for an extended period of time, would you say he was a right winger and are happy with his performances there? Pereira has played mostly as a wide man the past two years - his first two in senior football - do you think in the future anyone’s going to see the right wing as a potential position of his? Schweinsteiger came through the ranks as a right midfielder but once he established himself in his true position no one would have entertained the notion of playing him out wide. There are countless examples of players being played out of position at any stage of their careers.
Sanchez has excelled in left wing, no.10/ second striker and striker roles at Udinese and Arsenal, and has been a shell of that player when playing on the right for Udinese and Barcelona. He can only play there in the same sense that Martial/ Rashford/ Lukaku/ Mata/ Lingard/ Pereira can - you can play him in that role, but make no mistake he’s out of position.