If he's a fast trainer, I recommend you to be more patient on him. When I took over a level 1 team, my highest quality MC played very poorly with rating 5 for many games. However, probably after gradually fitting into my strategy, he gradually played very well in most matches even though he has some poor games occasionally. As your team is in low level, you may still win many games despite one player play poorly.

I agree that it is the hardest to find a good MC. I never have a MC who play very well forever. So I should maintain sufficient player on this position for rotation. In contrast, fast trainer is trained well forever.