By Felix Keith The January transfer window is a notoriously difficult time in which to do business, with desperation often leading to bad signings. Manchester United, like every club, have had their fair share of flops in the transfer market. For every brilliant one in January – think Patrice Evra and Nemanja Vidic – they have endured one that has not worked out at all. With his side struggling for form this season and new leadership to impress now in place, Erik ten Hag will be trying to avoid such pitfalls this month, with United beginning January by offloading the likes of Donny van de Beek…