The reasons Ferguson could afford such a loose shape in the final third were that (a) Ronaldo, Rooney and Tevez were all highly versatile, happy to play either on the wing or through the middle, (b) The three had a wonderful understanding in and around the penalty area, meaning Ferguson could effectively hand out three ‘free roles’ and sit back and witness the results and, crucially (c) All three understood their defensive responsibilities.
Of course, the key feature of the side was, in a move often described as being influenced by Luciano Spalletti’s 4-6-0 formation, which featured no "pure" strikers - United featured no permanent frontman. Ronaldo was primarily a winger, who developed his game both technically and physically to become both a goal threat from the wing, as well as a powerful presence upfront when needed – whilst Rooney and Tevez were small, creative forwards who liked dropping deep and were both extremely hard-working.
Manchester United's 4-4-2ish (or 4-3-3 if you may) shape in the Champions League final, where they defeated Chelsea on penalties.
Player Roles and Duties
Player roles and duties, corresponding to the XI of 07/08.
G (Defend): Van der Sar
Full Back (Support): Brown
Central Defender (Defend): Vidic
Ball-Playing Defender (Defend): Ferdinand
Wing Back (Attack): Evra
Central Midfielder (Defend): Carrick
Deep-Lying Playmaker (Support): Scholes
Wide Midfielder (Support): Giggs/Hargreaves/Ji Sung
Inside Forward (Attack): Ronaldo
Attacking Midfielder (Attack): Tevez/Rooney
Deep-Lying Forward (Support): Tevez/Rooney