StevO is absolutely spot on!
4-5-1 has been our most successul formation by far under Moyes, it's also our most attacking.
We have midfielders capable of scoring (Cahill, Arteta, Osman), and we midfielders capable of grafting (Neville, Fernandes, Carsley).
We have 5 forwards of varying qualities and we're pretty solid at the back these days (mostly).
AJ has to be No1 when he's fit up there on his own. If no AJ, then Vaughany is a very similar type of player. Very fast over the turf and capable of bearing down directly on goal. If no Vaughany, then Victor it is also quite capable to sit up there alone. He offers good link up with the attacking midfielders and can also run at defences direct and put the shits up them.
BT? He can cut the oranges in half for half time with McFudge!
At the end of the day, 4-5-1 is an attacking formation. The midfield is where the game is controlled. If our midfield has the right mixture of grafting ball winners and attacking wanna be strikers then by default we will be strong and launch more attacking play.
DM should build the team / squad around this need and only then will we be able to seriously start to challenge regularly.