You walk into the morning, open MAX, and yesterday's revenue is down 20–35% compared to the rolling 14-day average. Nothing else changed in the product. No big traffic shift. Just eCPM, gone.
Below are the five things you should check, in order, before you panic-DM your AppLovin rep. Each takes 3–5 minutes. By the end of 30 minutes you should know which of them is responsible.
1. Is one specific bidder failing?
Open the MAX dashboard, switch the view to Network instead of Ad Unit, and look at yesterday vs the 14-day average per network. eCPM drops are almost never uniform — they concentrate on one or two networks. If Meta dropped 60% on rewarded video and the rest are flat, you have a bidder failure, not a market shift.
The first move is to drop that bidder out of the auction for one ad unit and see if the other networks pick up the impressions at the previous eCPM. If they do, you have your culprit — re-enable it and ping the network rep with screenshots.
2. Did your country mix shift?
Switch the view to Country. A common pattern: a UA campaign ran cheap LATAM traffic overnight, your impression share from Brazil went from 4% to 22%, and your blended eCPM dropped accordingly. Brazil isn't lower-quality, it's just priced differently. The fix is not eCPM-side; it's either pause that UA channel or accept that blended eCPM doesn't reflect a problem here.
3. Did you (or someone on the team) change a floor?
Check the audit log on the affected ad unit. A floor raised from $1.00 to $1.50 will often cut fill 8–15% and drop blended eCPM if the lost impressions were high-fill, low-price. Aggressive floors only work if you have enough demand at the new price; the symptom of a too-aggressive floor is exactly this — eCPM down despite the higher floor.
4. Is your top ad unit out of inventory?
If you sell direct ads or have a programmatic guarantee that exhausts mid-month, your rewarded-video waterfall might be falling back to lower-priced demand. Check the volume on each line item. If your premium line is at 0 fill but everything below is unchanged, you've depleted your guaranteed inventory.
5. Did MAX release an update that broke something?
Less common but real. Check the MAX changelog for the last 72 hours and the AppLovin status page. Mediation SDKs occasionally ship regressions on specific OS versions — Android 14 + MAX 12.x has shipped two known regressions in the last 18 months that caused exactly this symptom for some publishers. The mitigation is to roll forward to the next patch version (12.x.y+1) rather than roll back.
The general rule
Blended eCPM is a result, not a cause. When it drops, treat it as the alarm; the diagnosis lives one layer down — per-network, per-country, per-ad-unit. The first 30 minutes of triage are nearly always cheaper than waiting for the rep to respond.
If you don't want to do this manually every morning, that's what we built Mediation One for: each morning it ingests yesterday's data, finds the per-app/network/country anomaly, and tells you which of the five buckets above is responsible. Free audit takes one CSV upload.