Many of our players get trashed all the time. Last season it was Pereira, Lingard, James, Pogba etc. This season Martial, Lindelof, De Gea have all come under heavy criticism.
If you play at Man Utd, you will play under heavy scrutiny and pressure. Its part of the job. If you have a bad game, people will criticise you. If you have 2 bad games in a row, more will come your way. Many bad games, and ohh boy. Nobody's gonna stop it just because the player is playing bad every game, infact its gonna worsen. That's why players get dropped. If you cant handle it(many cant), you're not Man Utd material.
Anyway, this is not a defence of the horrible racism. That shit needs hard hard punishment.
Playing when you're injured and then playing badly is not brave or commendable. Nor is it smart. Its counter-productive. He doesnt get excused for playing badly because he's playing injured. If you're a liability, get yourself treatment first ffs.