I agree that Paul never left, but he clearly seems more athletic and fit than I remember him being the last two years. The last two seasons when Paul dunked, it was always kind of a joke, like "haha, Paul confirms he can still dunk it." This year he's exploding into it and throwing it down with a lot of power. You can see it with his rebounding too.
Perk is another one that's really impressed with his explosiveness this year, but that's another story.