Agreed, Mascherano raced 20 yards and was very aggressive to the ref. He deserved his red. You just don't do that regardless of which decision goes against you.
Mascherano can be a twÄt sometimes and I just don't think he that smart a lad to be blunt. He should learn to channel his aggression better.
However, this kind of cardmanship should be dealt out to EVERY team. Rooney deserved cards the other night IMO as he was well out of order and this is where the problem lies. This kind of punishment, justified as it is, is just not meeted out on a consistent basis and it should be.