Barmby will find it harder to get on the bench as he is a kind of luxury to have on there, same goes for Cairney in a way. With 5 you have to choose 5 you can rely on always, in other words more boring players like Harper.
Only when all 4 strikers and the 3 central midfielders are available. Once Stewart is back it should cease to be an issue, to effect the same kind of change we can either move Koren into the middle and bring on the 2nd winger so that Brady and Stewart are out wide, or have started with the two wingers and bring Koren on as the impact sub.