Maybe I can agree that United have temporary difficulties in defense, but definitely not with the fact that they are weak in midfield. I think that this is their strongest line and if it is normal then such a weak (relative to top clubs) opponent like Leicester will have no chance despite some weaknesses in United's defense. I think in this match United will be the clear favorite and will achieve an easy victory.
I don't think Manchester United has a coach who is able to take full advantage of all the players they have purchased. Even though I really believe that the existing players, Man United, can compete with City and Chelsea. But from the few matches that have been done it is not what I expected. When they can't break through their opponent's defenses they are too rushed and confused. It caused them to be overwhelmed during the counterattack. And that's what currently needs improvement at Man United.