Nothing fishy about the general point the article makes though. NPD doesn't track 100% of brick and mortar stores and tracks even less in the digital realm and thus anything they say is just an educated extrapolation exactly the same as VGchartz is.
The difference lies in the fact that their sample size is much larger and thus they are in general more accurate. But hey, you can't complain when the numbers here are free and easily searchable and cover the whole globe instead of just one country.







