The rags are still winning games due to the myth and aura from the Ferguson years and probably prior. They lost a bit of that with Moyes and Van Gaal but a few good results, the media hype and Mourinho have clawed it back a bit. Teams will watch them and think, " Yeah we have a chance here" then go out and freeze a bit.
The truth of where they are lies somewhere in the middle. They are not as bad as a lot of out fans portray them and not as good as the media hypes them.
The derby is a one off and anything could happen. Both teams have the ability to turn the other over given a slice of luck and the decision's. We could batter them but,I know this will be scoffed at, equally they could do the same to us.