The 53-year-old becomes a key appointment at Old Trafford as part of United’s off-field overhaul following Sir Jim Ratcliffe’s arrival at the club.Wilcox joined Championship side Southampton last summer as their director of football, making the switch from Manchester City where he developed a reputation for nurturing excellent young talent as well as recruiting some of the best prospects in the game.A United statement read: “Jason Wilcox has joined Manchester United as technical director with immediate effect.”He will work with all technical areas of the football department to achieve the…