So either:
1. AniHawk is found to be lying, shaking the very foundations of sales-age on gaf.
-or-
2. NPD are just being dicks, trying to cover up their numbers and make AniHawk look bad. This will make gaf like NPD a little less, but gaf will continue to put up with NPD's shenanigans just so they can discuss "real" numbers.
I'm leaning towards the latter.