Originally Posted by
Coal
I think you might be confusing the BB "playstyle" and the normal Unholy AoE rotation (which includes BB).
The BB playstyle drops FeS completely and uses BB on blood runes, IT on frost runes, and SS/SR on unholy/death runes. The devs nerfed BB as a consequence to prevent this playstyle from surpassing the intended Unholy playstyle with FeS.
The normal Unholy AoE (2+ targets, so anything but single target) rotation uses BB on both blood and death runes. You can convert the frost runes to death beforehand with FeS or with a couple of ITs if you need to switch to AoE immediately.