Lots of numbers, non of them tells us how many units it sold compared to previous Halos.
It's like saying GT6 flopped because it only sold 5 millions, it didn't flop, but it didn't match previous GTs. That's the real argument. No one is suggesting Halo 5 or GT6 have flopped.
GT6 under-performed, Halo 5 is currently under-performing in the UK, X1 biggest market in Europe, and the only European market with an xbox userbase that's comparable to the previous generation xbox userbase, so naturally, it is doing worse in the rest of Europe. The game is pretty much destined to sell worse than Halo 3 in Europe.
We'll see how it does in the US.