A big part of Man Utd's success has always been the fact that they don't do losing runs. Sure Ferguson lost some games here and there, but three games on the trot? He always knew how to re-instil the core belief he had in the players and turn it around when they lost a game.
I don't think Moyes has that. He can't call on the 'I'm Sir Alex Ferguson, I don't lose' factor. If Utd lose three games in a row the narrative would become Moyes can't hack it, they never lost like this under Fergie. The players may well turn under that pressure.
And I think Utd can lose three or four games in a row this season. The squad may have won the title, but a large part of that was down to Van Persie, and Ferguson's meticulous planning. He may have had to call on Carrick at centre half a few times last season, but he never let the deficiencies in the squad expose the holes that are there.
Their best centre backs are both old and injury prone. Their midfield is very unbalanced. The shield is basically Carrick or Darren Fletcher (and who knows when he can play, or how much). A few injuries, a few losses and the media gets to bite. I'm not sure the squad would rally under Moyes as they would have under Ferguson.
I still think they'll finish high. In fact I think Chelsea are the most vulnerable of the 'Big 3', but I don't think they are certs for a challenge this season. They are definitely vulnerable if the fates conspire.