Yes I used to have more or less balanced skills in the lower levels of the game but recently I thought I would trial out 'unbalanced' skills on all players, weight defense to defenders and weight attack to strikers to see if it is more productive for strikers to score more etc, I think you should not weight your players more than 10 points from best to worst... A 95 quality defender could have 100 def, 90 att, 95 p&m. but I wouldn't go something like 110 def, 90 att, 90 p&m for a defender.