The fact that he was at 3 all through 2016 and his average dropped by 10 points notwithstanding? Would it not just be a case of spoiling what you have while not solving any problems. I hope they put Liam straight in at 3, it's where he want to be, it's where he should have been 18 months ago, and it's where he's most comfortable.
I think this whole thing of him not taking responsibility is garbage. This isn't one day stuff and he might have to be fully on it for full week, so let's give him the best possible chance to succeed. He's the skipper, he's the most important player in the team, and he's most comfortable (and most effective) at 4 so let him get on with his jobs. At least you've dropped this claim that he's refused to move.