Hopefully by the first day of the new season, there shouldn't be any decisions to be made anyway.
Any decisions that affect the riders, should be decided upon (where possible) by the riders.
The DD person will essentially be a point of contact for the riders, sponsors and club(s) who run the series. I'm sure the MT will have a level of responsibility when it comes to dealing with Ducati/Shell/Pirelli etc. but the day-to-day running etc will be dealt with by this one person.
Much like the money is dealt with by the treasurer, and the memberships by the membership sec, and the chairs by the... well you know
That's my idea of how it should work anyway.
This person needs to be pro-active and help promote the series, not just handle questions and run votes etc