Yeah their numbers arent weirdly assigned. I think the GK is good, and bored.

MC's you have to experiment with. It depends on so many things, where you play them; do you expect them to be all round, offense or defense? (I will say that even on my team with phys stats very high the MCs and DMCs seem to need it the most) and some like arrows some not, etc.

Ratings for these two roles in particular tend to be lower. If you watch the match to see what they do it sometimes helps to evaluate if they are bad, or just not getting to interact with the ball.