Injury is a part of Football game...no need to be over reacting...It's a risk that every professional player aware most.
Due to Red Card for Fellaini, Mourinho did not have any other choices except strengthen the midfield. and for the sake of that he will emphasize to player who have physical asset.
That's why TFM is being played. And even it's not special, he did his job sufficiently. Him being injured just another sad story of this season, but it's not Mourinho fault.
Hope that even his body is injured, his mentality is being stronger. He should think this as a stepping stones to be better...as a youngster, to be played in Manchester Derby, among great players and not loss the game...he'll proud himself for that...