Don't let facts get in the way of your little fantasy.
So let's have a look: do you mean the 09-10 playoffs where he averaged 0.7 assists in 34.4 minutes? Or are you talking about some fantasy playoffs where he actually averaged a decent amount of assists? He had one good series (I'm charitable) against Dallas where he indeed scored 29 and 21, with 4 assists in 6 games... which is consistent with what? With being a shooting guard! Shocking!
I'm going to be really nice and take his best 23-game stretch at the end of the 09-10 regular season, when he played 36.7 minutes per game (which by Spurs standards is a lot of minutes--Parker never averaged that over a whole season), he scored 16.3 ppg and got 4.3 apg. Now I'm not going to be so nice with Parker and will look at his numbers over his whole 2nd season, when he was 3 years younger than Hill: 33.8 mpg, 15.5 ppg, 5.3 apg. Hill during his best stretch wasn't even as good as Parker over a whole regular season...