Your second goal was an open shot, which was deflected and served to you on a silver platter. There was nothing about luck in this game. Steckelenburg had three or four really good saves, but otherwise all this possesion led to extremely little vs. the worst defense of the EPL.
This performance is mainly down do Moyes. He set the team up that way. Not a single team in the world plays in such a way with a overreliance on one thing (crossing), if they are not clearly told to do so.
People also need to realise that this is the way Moyes wants United to play. Mata, Januzaj, Rooney or RvP are all capable of taking different approaches towards the game, but are not doing it.
Moyes needs to go. There is not another way to say it. I have trouble remembering a similar case of a manager regressing a team in such a way over half a year.
You used to be a team that was feared. Now the dead last team subs offensively at HT because they smell blood. You used to be able to turn games around at even the last minute, now you are eating goals in extra time like they are candies. All this mental strength is gone, because you are coached by a negative manager.
Let him go as soon as possible and bring someone in with a clear idea, who gets to install it without pressure about results. This is the best time for a new coach to start a transition, because the season is already a write off. The longer you wait the deeper you will fall.