CTR is WAY up this month because of the new square button text ads.
Had a huge day yesterday, my site has skyrocketed in the rankings
Not sure how this supports the "square button" as the cause of the increase. Seems to me an influx of traffic is partly to blame for your success as well. Just pointing out that there are seemingly two variables involved rather than one. Anyway, sometimes it's best to not look a gift-horse in the mouth so congratulations are in order! Yesterday was pretty decent for me too. Hope it holds for you.
US CPC was in the toilet most of the month (I use disqus ads on my site and the disqus ads were beating adsense from a CPC standpoint for several days). Luckily the rest of the world has oddly enough had much better CPCs than usual. Had a $5 click from the netherlands the other day. Go figure. Slowly recovering to averages. US CPC is still suffering though.
There was definitely NO correlation with traffic and CTR. My traffic has been falling this month. I just benefited from a big boost a day ago with a ranking increase. Before that, no, it was suffering, but CTR was up anyway since the square text buttons came into play. I HOPE they don't go back to the round buttons. I hated those.
CPC has been AWFUL this month. I'm glad it's not just me. It's been bad across ALL of my sites. I don't know what the hell is happening.
I feel like for my site(s) ad relevancy has been MUCH better the last few days making for a pretty good earnings streak. Fingers crossed the ads stay as relevant as possible. It's still amazing to me how "poor" the advertiser pool on mobile ads. Google can do everything in the world to make the ads look better on mobile, but if the majority of advertiser's are newbies who just don't know how to "bid down" on mobile devices the ad relevancy will continue to suffer and the CTR and RPM will remain low. On my sites, it's all the advertisers (mostly national) that I'd expect to see on desktop and tablet, but on mobile it's mostly pure garbage sites that no one has heard of. The advertisers are "relevant" in that they are selling products that are relevant to my content, however they have no brand and thus are not getting clicks.