So what you are saying is that because there are other players ahead of him in the pecking order (which I agree with), giving up is acceptable?
If it were me, I'd do everything I could to score a hat-trick in each of the pre-season games. I'd make people look up and pay notice. And after each of the hat-tricks I'd tell Jose who "the man" is. I'd also ask Jose to bench Lukaku and put me on instead. Jose loves that sort of confidence. He loves it when players stand and up be counted and show fight. Jose will be beaming ear to ear, if Martial did this.
I remember when
Rojo clashed heads and was bleeding from his head. He ripped off his shirt, which was full of blood and wanted to continue playing (which he did). Jose was standing nearby and could not hide the joy he was feeling when he realised that he had a player who would run through brick walls for the cause.
The players who Jose tends not to get on with are those that give up at the first sign of difficulty. And this is what Martial is.
It just isn't in Martial's mentality to show fight, stand up and be counted. He is too laid back for Jose's style of management.