You dont think grabbing a player by a neck and throwing him to the ground is a yellow card offense?
Yes it is, unfortunately he didn't 'grab' him by the neck he pushed him out of the way via his shoulder/neck.
Do you think rolling around on the floor holding your face pretending to have been struck is acceptable?
I agree the officiating this season seems to be worse than previous years but I think the linesmen/women have also got to take the blame, more often than not they only flag after the referee has blown the whistle. I also think every team has had their share of poor decisions and not just exclusive to Man Utd (I also think some fans and especially Jose are using it as an excuse when playing really poorly rather than looking at everything).