In reference to both sides, he writes that 'both could be described as ageing teams that needed breaking up, but with issues over those brought in as younger replacements'.
Hansen argues that if the Red Devils do not bring in the required young talent, they will be left behind in the notoriously difficult league that is England's top division.
He adds that the secret of success is 'strengthening while you are on top, regardless of how you won the year before'.
Despite Moyes' best efforts in the transfer window, Manchester United failed to strengthen significantly, with Marouane Fellaini being the only major signing. The Belgian has so far not managed to make a real impression at Old Trafford.
After Saturday's defeat to West Bromwich Albion, United sit 12th in the table, behind the likes of Southampton, Hull City Tigers and Cardiff City.
Nobody is expecting Moyes' side to remain below mid-table. However, with the rise of Tottenham and Liverpool to apparent title contenders, the battle for the top four is starting to look even more competitive than it has been in recent years.
Spurs' remarkable performance in the transfer window has left them with a squad that is full of talent and depth to cope with injury. Liverpool have the returning strength of Luis Suarez; as was illustrated on Saturday when he grabbed two goals on his return against Sunderland. The Uruguayan is also forming a very productive striking partnership with the in-form Daniel Sturridge.
As well as the realistic new challenge from Liverpool and Tottenham, United also have to fight against Manchester City, Arsenal and Chelsea. Having been beaten 4-1 in the Manchester derby, the Red Devils will be in no doubt about the strength of City's squad in comparison to theirs.
Whilst Chelsea look weaker in attack than they have done in recent years, Jose Mourinho's ability to lift teams will make Chelsea top four contenders. With the signing of Mesut Ozil, as well as the renewed axis of Jack Wilshere and Aaron Ramsey, Arsenal will also be tough to beat.
Clearly Moyes' side have an immense amount of competition to deal with if they are going to achieve a top-four league position. The chances of United retaining the title does seem remote, and the old adage that 'you can never write United off' perhaps holds less weight now that Sir Alex Ferguson has retired.
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