In my books Kaka's second yellow was not justified, but I'm not a referee. I think (don't know if it's the case with bobby) that having watched the physicality of the premier league for nigh on 12 years, that this has influenced me on judging what warrants a yellow card. Taking consistency into account, considering the referee who sent off Kaka, if we applied his standards across an average premier league weekend then a lot of games would finish with about 2 players on the pitch.