Castiel said:
Talk about hyperbole. If you think anything Luiz does in that gif is wrong, then you'd have to agree Yaya, Kompany and Zab at least all deserved reds several times over in that game. It was a completely unjustified retaliation to a simple hand off however you look at it. He better score a hat-trick against Spurs now.
Luiz is a dirty bastard, he's always flinging his elbows every single game. How he's got away with it so far is a mystery. That said, Sergio shouldn't have reacted the way he did and it was a straight red no question. I will say that he was obviously infuriated with Luiz and that's why he saw the red mist. It's the first time I've ever seen him react like this and it was completely out of character.
The rake down the back of Sergios leg by Torres in contrast was completely cynical and just as deserving as a red card. You could argue that it was worse because it was pre meditated rather than a moment of madness like Aguero.