Blizz, I know there are addons, but can you just add a DR tracker into the default UI that you can enable or disable.
Tick box options could be;
-Enable in Arena
-Enable in BGs
-Enable in World
Then add an Edit box for placements you want. Like show above enemy frame, or show on arena frames, or both. Could even be part of the PvP frame widget, and you can choose where you want it, e.g. Left of the frame, right of the frame, within the frame.
I don’t think this would be a difficult thing to add. Something like this should be in default UI options imo.