#2 Tactics
Manchester United has built a solid reputation and success around the foundation of fluid attacking and a compact defensive setup. This has seen the team have an admirable win record even in the face of conceding goals.
Mourinho's has shown to fancy cautious play which has allowed the even inferior opposition to gain confidence when playing United. That is why teams such as Burnley and Watford could still cause United some problems despite being two goals down at halftime.
Wolverhampton Wanderers exploited these tactics at Old Trafford of all places and got away with a point. United need a coach with an all-out attacking mentality that will restore the fear factor in teams. One is never sure the type of Manchester United that will come out of the tunnel regardless of the opposition's pedigree.