Also, I don't think its good game management at all by the referee. To give a 2nd yellow, esp so soon after the 1st yellow, for me, you are really looking for a stick on, something that even the player himself can hold his hands up and basically walk off the park. You are looking for the 2nd yellow here to be one that nobody can argue with. Esp so close to half time, he had ample chance to say to Walker, "look, that's close to 2nd yellow, take the half time and don't give me reason to notice you in the 2nd half". That to me, is game management.
The YC for Everton late on is so typical, it a token red, just to somehow make it seem like both teams played with ten men. damage limitation. If, Oliver is the one calling a 2nd YC for the City player, then I would like to think the referee would be brave enough to say "thanks for your input, am happy just to warn".
then again, its always easy sitting watching the game back from comfort of living room !