How to decompose a falling win rate into its real causes

How to decompose a falling win rate into its real causes

Win rate (the share of auctions you enter that you win) dropping is a symptom, not a diagnosis. Decompose it in this order before touching bids.

1. Split win rate into its two factors: bid rate (auctions you choose to bid on) × clear rate (bids that win). A falling number could be either; they have opposite fixes.

2. If bid rate fell, the cause is upstream of the auction — pacing throttled you, budget capped, or a targeting filter tightened. Check your DSP's bid-eligibility logs, not the auction.

3. If clear rate fell, segment by floor exposure. Pull the share of lost auctions where your bid was below the published floor versus lost to a higher competing bid.

4. Floor losses mean a publisher raised floors or moved to first-price; competitive losses mean demand intensified. The first is solved by floor-aware bidding, the second by valuation.

5. Finally, segment competitive losses by margin. Losing by 2% across thousands of auctions is a tractable shading problem; losing by 50% means you've simply mispriced the audience.

Why it matters: Buyers reflexively raise bids when win rate drops, but if the cause was a pacing throttle or a floor change, raising bids just burns margin on auctions you'd have won anyway. The decomposition tells you which of four distinct problems you actually have.