If the fans are happy and saying they're back inform after winning against Leicester since the exit of ETH then they deserve it I mean the fans, is been long since they won a game with that margin and to them they are on top of the world, let them (UTD fans) celebrate while stock last.
Manchester United haven't played as good as they did against Leicester in a very long period of time even in the pre-season they haven't but they shouldn't start jumping for joy yet because they can't get a win against Chelsea, is still not yet the time to celebrate. To me is like they felt relieved after too much negative atmosphere around them, now they can play what they know.
The fixtures they have ahead is not an easy one, in fact since this season no fixture has been easy for the Red Devils so they should be ready to face their fears. Let's see how the Red Devils will perform against Chelsea, PAOK (Europa league) and Leicester City before the break and let's see if they can finish on the top 10 of the table.