If you look at the picture, it shows that one if the MC's arrow is pointing down. So I played one game with just an MC who slide into a DMC with the arrow down. His rating dropped. Then I tried to do the same thing with a player that is besides a MC also a DMC. His rating stayed the same or went up.
So I think that if you put an arrow on, the player moves one up or down. I think it is important, that your player should have the positions that you want him to play in order to keep the rating up. I tried the same thing with a DC and a DC/DMC. In the end the player with the additional position turned out to have the better ratings. These are just my findings. But overall, I have not lost a game using this formation. Don't get me wrong, I am sure that there is somewhere a counter formation for this on. Maybe some center based like the 41212 ND etc. It is just to experiment