When mobile game ad revenue drops, it is tempting to open the ad dashboard and check one number first: eCPM. If eCPM is down, it feels like the answer is obvious. Demand is worse. The network is paying less. Maybe the mediation setup is broken. But in practice, eCPM alone can be a misleading first signal. For small mobile game and app teams, the better question is: Which driver actually changed first? Revenue Is Not Just eCPM At a simple level: ad revenue = impressions / 1000 * eCPM That means r