Over thinking goes with the territory
Joking aside, yes sometimes you do just have an off day. I think seeing the same team, who battered utd away, struggle against a poorer team at home, bearing in mind we rarely lose at home, automatically leads to what, for me at least, was the obvious reason. It's sort of backed up by the fact that Forest took the opposite approach, the one I'm arguing that we should have used. Played four of their usual starters and added in those who had been away. Obviously this isn't a failsafe winning formula but it was that day.