I mean it was just one example but sticking with it for argument sake, Greenwood just played a simple pass wide, kept his momentum within the move and made a really good run which almost forces the players behind him to play that ball over the top to him, it doesn't really matter about what Lingard and Mata are doing, they don't dictate Martials movement, I would ague it to the contrary, with Martial's sheer lack of movement limiting the options for Lingard and Mata.
It sounds simplistic but one simple action would transform Martial as a number 9 (or at the least give him a chance there) but I don't think he's capable of it, or should I say willing or intelligent enough to do it...
That's to receive the ball, pass it simply wide or back into the midfield and spin in behind give the defenders a problem, stretch the play, vary the attack. He will refuse to do this, time and again for entire games.
He refuses to do the basics of a number 9 and make a run in behind the defence. Instead he drops deep where defenders can predict him, he want's it to feet, holds the ball, turns and tries to run past five defenders. His dribbling is good but not good enough to entirely ignore the fundamentals of number 9 play and to make zero runs off the ball.
He's basically learned nothing from Ole or Cavani especially which further strengthens my feeling of it being a lack of intelligence.