No way Martinelli could play 9 for us, he's even worse suited to that.
His first touch isn't clean enough and he's not strong enough in duels to out-muscle central defenders (it's not just about height and strength either, even Jesus is pretty good at winning those balls).
Bottom line he's a great player but he doesn't quite suit our system and Arteta's not about to change it. We are clearly committed to territorial domination and high pressing.
Martinelli thrives once play breaks up and becomes more open, but with our slow scoring he's usually been exhausted and in need of being subbed by that stage.