Field note
Reading eCPM after a mediation swap
· eCPM, mediation
A mediation change rarely lands as a clean before-and-after line. Fill rates shift first, then match rates, then the eCPM your finance sheet cares about. Teams in Bangkok often call us after a “successful” swap that looked strong for five days and flattened by day twelve.
Start by locking the comparison window. We prefer two full weeks before and after the change, excluding any UA spike or store feature you already know about. Compare rewarded video separately from interstitials; blending formats hides which partner actually moved.
Watch impression share by partner, not only blended eCPM. A new bidder can raise the top band while shrinking volume on a mid-tier network that used to cover off-peak hours in Thailand. That pattern looks like a win in the headline number and a quiet loss in daily revenue.
Document the floor and timeout settings you touched. Many “mediation wins” reverse when a timeout that was shortened for a test stays in production. Keep a one-page change log next to the console so the next reviewer is not guessing.
If the settled eCPM is still below the prior band after two weeks, treat the swap as incomplete rather than failed. Revisit country filters, ad unit mapping, and whether the creative set still matches the new network’s preferred sizes.