Originally Posted by
Irwanda04
In a association, all managers are equal no matter their level, a 6 stars players for level 5 is same as a 6 stars players for level 50, their quality is counted by how many stars they have and not by their quality per level because in this way you are free to group with any manager no matter of what is his level.
The answer for your problem is because he plays 100% on his level, so in association he plays with 100%. But you play as -1 level, you will face a team with 120%.