Well the GC did incredibly well in North America; if we look at PS3 and 360 data you'll see a similar trend, and I wouldn't be surprised if the GC outsold them in the first year.
It's the Worldwide picture which is key here, as opposed to one area. Sure, the Wii U is doing poorly, no-one is denying that. But trying to hammer home your argument without giving us all of the data is somewhat disconcerting.