You're assumling only what Kesler does offensively.
Kesler is effective at faceoffs and defensively he can play against the other teams top centers. The defensive game of Kesler at the centre position is very important.
I wish more people would realize this. The "positions" are there for defensive play and that's where you have to be disciplined and maintain your given spot (C,RW, LW etc). Once you cross the centreline, you become three forwards on the attack and you no longer become c, rw, lw, but F1, F2, F3.
Offensively, it makes no difference if Kesler is the Cman or winger, but in the defensive zone he needs to be in the middle. I don't see AV ever moving him to the wing. I know MG says that they're not looking for a winger, but if I'm him, finding someone who can play with Kes would be my priority, because over the last couple of seasons his play, offensively, has been more of a liability than an asset. If they can't find someone to play with him, they need to move him.