How do NX circulators work post-unleashed?

I'd like to mention that I've used over 100 non-NX circs(from medals of honor), and never have I ranked down. They seem to do what cubes do, as you said, 1st line = that tier, ones below are lesser ones with a chance of being that tier.

I thought the same since I used about 50+ circulators and I stayed at epic, never being bumped down to rare. However, yesterday I used one and was upgraded to unique (lines not relevant to me though) but bumped back to epic from the circulator right after. Could it be that you'd never be bumped down from the level that you were before the revamp?