Caught an interesting comment over on B&C:
judging from what Goulding has said elsewhere (namely thefirstexpedition) TBA went through some rewrites within the last month to a year - originally the conception of the series was going to have a DAoT link, where humanity attempts to use the Men of Iron to defeat the Beast. I think that got booted in favor of the impending DW release.
Yeah, I can see that. You really had an old tech vibe in The Beast must die. Unusually clean and straight rooms filled with what looked like old technology in the beast's lair. But then they hamfisted in the deathwatch and had their founding tied to the TBA saga, and by proxy, the Beast went from being a scheming gothic speaking mastermind threatening to roll the human empire completely, to just a grunting oversized ork warboss.
The high point of the series was definitely the beast must die imho.