Your explanation is basically almost the same as my post before. I think there is no need to continue this, repetition makes it unattractive. 

I don't know if it is a good decision or not, but he needs more chances to play. If he always sits on the bench, it will be bad for his career. Man United has already too many attackers, especially they have CR7 as the regular player for CF position. I don't see any chance for Martial to compete with CR7. Moreover, Man United also has Cavani with the same position. However, both CR7 and Cavani are old players, probably won't last in the next 2 seasons. Man United only has Martial as a young CF there.