I think what it is , and i have experieced the same , is if you win by a large margin and keep a clean sheet ,your gk will always get a low rating. This is because he has NOT had anything to do in the match and has not been tested.....so how can he be given a high score ? I also find as I progress up the levels in T11 that if i win by a large score and keep a clean sheet the gk's moral decreases as well...just purely i think because he is not getting involved in the match....