Should I use him?

[gamer5289]

Look at the above player.
Some skills are highlighted in WHITE and the other skills are GREYed out.
The WHITE skills are what are essential for a player to perform in the position he plays in.
The grey skills, not so essential, for that position.

White skills gain faster than grey skills in training drills.

Strength is greyed out for AML, and hence, considered a "non-essential" ability for an AML to perform effectively.

PS: Check some of the training tutorials on the forum if youre interested in this.