Question for stat guys

[furball]

I have a question for those of you who are big stat guys.  Or anyone else who happens to know the answer. 

When they do stats about a guy vs the man he's defending, is it the guy he is actually defending on each play or just his positional counter part.  In other words, if one of the Celtics guards gets beat off the dribble and the center comes over to help out and the other team's guard drops the ball off to the now wide open center who hits the shot, does that go against the Celtics center?  Or is he now considered to be defending the guard?   

[ScubaSteve]

There are so many different metrics out there now that I'm sure there are most likely a bunch of different metrics that take into account help defense like the example you used, and do not penalize the center for leaving his man to prevent a layup or dunk. But for the most part defensive metrics are measured using the stats of the opponent that the player is adjudged to be guarding. So the center technically would be responsible for the opposing center. There is just so much stuff to consider while measuring defensive metrics. Eventually someone will figure out a universally accepted formula for it.