The Scot, who was at the helm of Old Trafford for just over 26 seasons, is the most decorated manager in Premier League history and has, over the years, built multiple title-winning squads. Naturally, there are several players who could be thrown into the fray for the best signing made by Sir Alex.
Cristiano Ronaldo is an obvious choice for this tag given that he was the only one to have won the prestigious Ballon d'Or in a Manchester United shirt, and is one of only two players to have won it with a Premier League club. However, O'Shea believes that Ferdinand 'edges out' Cristiano Ronaldo in this regard. He said;
"I’d have to edge it to Rio. In my time, in terms of how consistent he performed. He provided such a solid foundation for the team. He was a great lad as well."
O'Shea explains decision to name Ferdinand over Cristiano Ronaldo as Manchester United's best signing
The Irishman, who spent the best part of 12 years at Manchester United since the turn of the century, believes that it is the impact that Ferdinand had on the side at the time that gives him an edge over Cristiano Ronaldo. He believed that this was the case despite the English defender's record price tag at the time after he joined for a whopping £30m from rivals Leeds United back in 2002.
"When he joined he really settled in well, he knew a lot of the players from England. He fitted in well at the time and proved to be a very good signing. People mentioned the price tag a lot but he provided very good value."
The Reading first-team coach added,
"Yeah, it’s close [between Ferdinand and Cristiano Ronaldo]. You are talking about two amazing players but just at the time, what was needed and the impact he made overall at the club, for me Rio just edges it."
Manchester United have made some massive signings in the recent past but have had varying levels of success in doing so. Since Cristiano Ronaldo's record departure to Real Madrid, they've broken the British record fees on a handful of occasions to sign players such as Angel Di Maria for £59.7m, Romelu Lukaku for £80m, Harry Maguire for £80m, and Paul Pogba for £89m.
After sharing the spoils with champions Liverpool in a 0-0 draw at Anfield, league leaders Manchester United travel to Fulham in midweek before hosting the Reds in the FA Cup.