Not enough improvement to warrant a thread. He'll never be good enough where it makes a significant dimension to his game so what you see now is as good as it's going to get. It's simply not worth improving your volleys to the point of them being a strength in today's game.
Well, his baseline game will always be better than his net game, so of course he's not going to stop being what he is. Rather I think the point is that his net game, slice and overheads were in such condition that even this level of improvement is noteworthy