That's not quite how it works though. Even McGeady came back at times, he wouldn't just stay up front, nor would Sinclair.The amount we would gain from letting our left winger just stay up front would be far less than what we would lose by doing so.
Can't just expose your left back all game, you'll get battered
However if you give the players of the standard that McGeady was and Sinclair is, that bit extra creative freedom, you will benefit from it.