Is there a place to collect data on how many fouls a player suffered that incurred a yellow (or red) card (and/or penalty?) I'm asking, because I'd like to try to quantify The Great Endless Jozy Altidore Debate; the point being that I believe he created a great many cards / penalties, and obviously, would like to find some comparative data. The additional question, what is the attacking value of drawing a yellow card foul? (The value of penalties is obvious, the expected conversion rate of penalties for the team) This one, I don't know how to do, but it seems an interesting question.
It may depend on what percent of players who get a first yellow card in a game end up getting a second card and sent off. Players may be more careful in how they play to avoid getting a second card once they have one card, but there's no easy way to quantify that.
I agree there's no way to quantify how a player modifies his play after a yellow card. But I think the proposition that a defensive player does modify his play to prevent drawing a second card is self-evident. Number of fouls before and after a yellow card? Number of tackles before and after a card? In combination, that might give you a defensive aggressiveness index you could look at. Defensive Aggressiveness: SUM of FOULS/90 + TACKLES/90 = DEFAGGRO Is that a worthwhile stat? Should it be a straight sum or should they be weighted somehow?