Having seen a significant rise in mobile use this year, and noticing some pages with high mobile use have a very poor "Active View Viewable" percentage, I decided to replace our top leaderboard with a responsive ad unit.
I've heard some negative things about the performance of responsive ads - so rather than leave it to Adsense, I took control over what size ad was shown: People with a screen big enough to see a leaderboard, get shown the leaderboard they would have seen anyway, otherwise, a banner or 320 ad unit is shown instead depending on screen size.
Result? A small boost in "Active View Viewable", but overall CTR is down, CPC is down and RPM is down.
Given that the only people affected by this change are seeing a whole ad instead of part of one, it's hard to see how this can perform worse than the previous setup - but it does. Presumably there's very little inventory available in the smaller units so prices are super-low.
I don't like showing leaderboards that don't fit on people's screens - it looks scrappy - but it's too big a revenue drop to go responsive at the moment.
Anyone else experiencing something similar?