Kagawa and Adnan might both benefit from interchanging freely rather than occupying relatively fixed positions. Kagawa, Rooney and Januzaj as the three AMs in behind RvP or Welbeck could be a brilliant combination as all three can interchange and play anywhere. I think our play would be less rigid and predictable with a good blend of crossing from wide areas (mainly from Evra and Rafa) and also playing between the lines more centrally, which we've struggled with this season because imo of the almost obsessive focus on width and the inflexibility of Valencia.
I've heard this expression used lots of times at our club referring to many forward combinations but it has never actually worked out like that. Even when we had Ronaldo, Tevez and Rooney we always kept a fairly stiff formation with their roles very rarely interchanging with each others.
The reality of it is that it doesn't require much of an understanding between those three players as the actual movement and switching is fairly simple, the trouble it creates is further back and the midfield finding the outlet and reading the play ahead of them both in attacking terms and knowing what areas to cover defensively and the fullbacks knowing whether they will be supported if they attack or not.
It provides too many complications as to who should drop back and defend and who should stay in attack, is it the one who has switched wide or is it the one who started wide? What if a play breaks down and there is a fullback and a winger attacking one of our flanks and we've got two players central?
There's a reason teams play formations and give players roles and duties in certain areas of the fields and there's a reason why it's only ever one player given a free role because you can have 5 players around him aware of their duties should he move out of position and into theirs. Having 3 players in free roles is chaos.