i have tendency to assign attack attributes to strikers, balanced attributes to defenders and midfielders, and defensive attributes to goalkeepers. i don't think it's a good idea to just focus on defensive attributes to defenders since some of their basic attacking attributes will suffer, like passing the ball. some of the defenders also have tendency to cross and shoot from outside the area and attacking attributes will help them getting goals or assists. i notice that when defenders shoot from outside the area, the one who will block it are opposition's attackers. if the attackers do not have good defensive quality, then it all depends on the goalkeeper. so, i think balancing attributes on defenders also increasing probability of goals. that's what i think. please correct me if i'm wrong..