Probably has something to do with the fact that teams tend to put the best inside defender at center. I play my best defender at PF, because I noticed that that is the spot I need more defense. At least so far has worked out OK.
with this theory the pf should have the better matchup rating ;)
I tend to the point, that he just get more oppurtunitys, because he plays a more "mobil" positions and don't get all his passes to the hoop.