During the Beta when they announced that they were adding diminishing returns to avoidance, they did so to include that the following things were diminished:
1.) Dodge% from Dodge rating, Defense rating, and Agility
2.) Parry% from Parry rating, and Defense rating
3.) Miss% from Defense rating
I highlighted rating to remind that Defense skill is not subject to or a participant in diminishing returns. Currently, of course, the only way to get defense skill is from rune of SSG.
I honestly don't know what the *actual* relation between the stats contributing to dodge is, but I do know they were generally left out of the consideration in looking for interactions because no one particularly stacks agility (rare few), and defense has only become of interest for people pushing the 'unhittable' cap recently.
If anyone has some more solid sourcing on this, it would probably be more helpful.
PS if Chill of the Throne is Sunwell Radiance, then we wouldn't be affected by it in the Citadel. =P