You are seeing very different things to the rest of us.
We press from the front now, Martial doesn't, he does what ever he wants to. That's not needless running, that's a game plan he is either unwilling or unable to execute. A front press doesn't work unless all your forwards do it.
If he's so clever, why does he continue to do the same thing he did on his debut over and over again? Drift out to the touch line, wait for the ball to feet, run at the RB, try to cut inside, get dispossessed or take a shot. Any decent PL RB can deal with that, especially when that's all he does.
He will leave us, but not this summer as he'd just signed a big fat contract, but next summer after another season of being a disappointment and not developing, he'll leave and end up at a second rate European club which will be the beginning of him bouncing around to a new club every two seasons because he's 'misunderstood'.
He has done nothing in his time at United to convince anyone he's going to be world class. In fact, everyone who's managed him have said, hard work beats talent all day long.