Now that the changes are out I feel like Watchman/Anni is still lacking and buffing merc slash buff duration doesn't do much for PvP.
I propose giving Watchman/Anni the same type of buff that madness just got.
Madness
In addition to previous effects, Devour now makes your damage-over-time effects uncleansable. This affects Creeping Terror, Discharge, Crushing Darkness, and Affliction.