I think its a players learning curve. I used to play hard attacking with normal tackling, i switched to attacking and easy tackling and it took a while but the cards have come right down. Also how have you applied all of your skill points? I imagine a player with a higher aggression rate than say passing or shooting is gunna be more likely to be carded and sent off... most of my players are at scout level with some even rated higher but 1 particular player of mine cant go a game without getting a card and his aggresion is higher than most but Ive chipped away at his stats and even though he never fails to pick up a yellow his sending off has been greatly reduced. Hope that shines a lil light on your probs as its worked for me.