Programmatic systems have finite request capacity. When traffic peaks above an endpoint or buyer QPS allocation, some eligible auctions are never sent, are sampled, or arrive too late to be useful. Bid volume falls even though page traffic and available impressions remain stable.
Separate request coverage from bid response rate. For the same time window, compare eligible auctions, requests sent to each demand path, throttled or sampled requests, endpoint latency, timeouts and returned bids. Segment by region and traffic peak because an average can hide a short capacity ceiling.
Fix the capacity bottleneck, traffic allocation or timeout hierarchy, then confirm request coverage recovers before evaluating buyer performance. Do not increase browser timeouts blindly, because a later bid still has no value if it misses the ad server handoff.