This is the average of the periodic unicast-packet delta samples UCS Manager took across the current reporting interval. It matters on an archived historical sample row of that same receive-counter set, kept purely for trending past intervals rather than showing the current live value because trending this average over days is how an admin establishes the normal unicast baseline for capacity planning on that link. An unicastPacketsDeltaAvg that climbs steadily from 3,000 to 9,000 per sample over a month on the endpoint this history row belongs to is the kind of organic growth that argues for planning additional uplink bandwidth.