yes, so not quite as bad as some are making it out to be, since the 400 million did have to come from somewhere
The only possible explanation other than NPD being wrong (unlikely) is the 400 million is the shipped amount (Sounds like something MS would do, though, make no mistake, Sony's played sleight of hand with numbers reporting in the past, lumping hardware together and so on etc... Microsoft doesn't own this kind of spin, they're just having to do more of it this gen than last).
Still, as I've said in earlier posts, Fallout 4 and November could very well be impacting sales in October as it has in December. Maybe Shadow can crunch some numbers for the last several Octobers, like he did with Dec.
there are still more posibilities, higher digital than usual for physical, most of the hardware for the month being halo bundles, more dlc bought, more hardware counted than people are thinking of. It was too vague of a PR piece. as for now, under a million could still mean in the high 900,000s people really shouldn't be hoping for halo numbers to be low, since it sold more than any other game this month.
Hopefully things will be all around better when we get the results for November