I would like if yellow cards would have less effect on players rating. If a player has rating 6, soon as he gets a yellow card, rating drops down to 3, or maybe 4. Is yellow card such a bad thing?! I dont think so. If he doesnt score or assist till the end of a game, it stays there (rating), maybe it goes up to 5, but only if he plays really good, for ex. defender blocks or steals a few posessions in short period of time. I dont think it is fair, yellow card doesnt automatically mean poor decision by player or something like that. Tnx!

I don't think rankings are so important. In fact, I believe that now, having a lot of possesion greatly influences the rating (regardless of a player shoots on goal, steals/block balls or gives good passes). You know if a player plays well by watching your matches.
Perhaps in the future the measurement of ranking is changed, but anyway, it's not too important.

I believe it's not important as well, once my GK held onto the ball for half of the match and he got a 10 rating :)

I'm not sure how important the ratings are but I know that a yellow card can make you more shy in tackles.

Ratings do not affect anything, they are not even saved on the server. They are just eye candy for us to look at. And I think this is good that way.