iDine/Rewards Network - OK - I'm officially confused!

Looking through my local Delta participants just now, they show either 10, 16, 20, or 40(!) miles-per-dollar?

Color me confused also! I did see one other post in another thread where a reported 40 MPD had been revised to 10, however, so maybe RN has some system problems. Not a problem if they let you keep the miles, of course... :D