United went crashing out of the Champions League last week and only managed a goalless draw at Blackburn on Sunday.
“All of a sudden, United are beginning to look short in the critical games, but when your midfielders are 35 and 36 years old, it is inevitable that it will catch up with you,” Hansen told The Daily Telegraph.
“If Sir Alex had just one problem in his team, he could spend £30 million on one player to resolve it. But when the problems run right through the team, it is a different story, and rebuilding United from here is going to be tremendously difficult.
“Defenders Rio Ferdinand and Nemanja Vidic have suffered from injuries this season, while Neville, Ryan Giggs and Paul Scholes are unable to produce the performances of their younger days.
“Up front, where United once had four strikers, they now have two in Rooney and Dimitar Berbatov, but Berbatov is not scoring at the moment.
“Ferguson does not have the options in reserve that he once had and there is no young Giggs or Scholes coming through to threaten the older players.”
“Breaking a team up and starting again is the hardest thing for any manager to do, but the next rebuild will be the hardest of the lot because we don’t know if the money is there for Sir Alex to do it,” he added.
“There are now parallels at United with what happened at Liverpool at the start of the 1990s. The team who won the title in 1990 needed to be broken up but, having been unbelievably lucky in the transfer market for 25 years, they suddenly became unlucky and you could say that Liverpool have never recovered.
“Twenty years on, Liverpool have still not won the Premier League and, while I am not saying that is what will happen with United, this is undoubtedly a crucial time for them in terms of reshaping their squad.”
“You just can’t see United taking advantage of any possible Chelsea slip by winning their remaining four games,” he explained.
“Chelsea have still to go to Spurs and Liverpool and they could drop points in both of those games, but I’m not sure that United can win at Manchester City on Saturday.
“Had Jose Mourinho been in charge of Chelsea, they would have had the title wrapped up six weeks ago.
“But until the medal is around your neck, you haven’t won anything and that is the one thing that United and Arsenal will be holding on to.”
