Doesn't the NEW ad copy also have to gain some sort of qualitative history (Quality) before it hits the premium position? Or is this position based on the ad group as a whole and a manual review?
PofC
I just changed every ad in an account due to some tracking URL changes, and every single one went back to premium within 2 days.
Changing ad text and adding new text have the same impact on your campaign - putting the ads back into the que.
It is possible under the new system that the entire process for premiums has changed, but from what I've heard, it's not happening - but with a new system, and potentially new algos - it's always possible other factors will be introduced.