Halo 4 is now ranked 6th, below Black Ops 2, Minecraft, Fifa 13, Modern Warfare 3 and NBA2K13. 343i take note of this, even with you trying to appeal to the casual audience with the introduction of new casual gameplay elements, you failed to not only appeal to casuals, but to your core fanbase.
We have a population thread for just this kind of talk:
https://forums.halowaypoint.com/yaf_postst183468_Daily-Halo-4-Population-Thread.aspx