avalon37 - 1:47 pm on May 6, 2013 (gmt 0)
This is a topic that I have spent a ton of time testing in the last 6 months.
I took over a VERY high impression site 6 months ago. When I looked at their ad formats they were opted in all types, but text was clearly the best performing. So I defaulted all ad formats to text only and earnings took off. Then Nessie happened. Post Nessie, at least for me, Google is basically making me opt into all ad types, but text version still works the best. However, before if I had all ad types text was still like 75% of the impressions. But Google now forces image/rich media ads on me at almost 75% of the impressions now. Basically if I want text ads I HAVE to run text ads only. And if I do select text ads only, the cpc prices drop significantly, so financially it's best for me to opt into all 3.
Google is forcing image/rich media ads on publishers like never before. This recent change has had a significant negative impact on my earnings.