He told TNT Sports: "I like him as a player. I think he is an excellent player but I just feel there is an issue. Is he the predator? Does he really want to get into that central position? And it almost seemed like he went back to type there. 'I'll wander into a wide position and then I'll feed somebody else,' but he doesn't really make the runs into the box. You have got to want to get there, it's got to be that desire to get on the ball and he can see the space but for whatever reason he doesn't want to get into that area; then they don't feed him. That's an area, perhaps, he needs to work on."
Keown added that the Brazilian may be reverting to type when he was playing in attack at former club Manchester City against Palace.
He continued: "It's just interesting that Pep [Guardiola] had him for quite a few years and decided to use him in that right position. That looked like the role he took up for Man City but if he is going to be Arsenal's centre-forward then they are going to have to do more work on keeping him in that central position but he works so hard for the team. He is an outstanding talent but I don't see him as a predator right now."