Richard Jolly for ESPN FC:
United have a tradition of attacking football. Much of it has revolved around wingers, whether with the Busby Babes, George Best or, more recently, Ryan Giggs and David Beckham, the best crosser of his generation. Van Gaal has players who can be described as wingers — Di Maria, Januzaj, Young, Valencia — but they have rarely been used as such. He has eschewed systems like 4-4-2 or 4-3-3 which would have allowed him to select wingers, instead preferring a 4-4-2 diamond or 3-5-2 when such players have either been forced infield, deployed in deeper positions or omitted.
If teams do not attempt to get around the sides of opposition defences, it leaves three options: to go over the top (which is difficult because Van Persie and Falcao lack pace in attack), to play through them or to go direct. Van Gaal’s preferred method is to play through opponents. Equally, that is the most difficult, especially when defences are packed and United lack the creativity to open them up. Hence the recourse to Fellaini.