This is the average of the several sub-interval byte-delta samples UCS Manager took across the larger reporting period for this object, smoothing out any single noisy sample. It matters on the live receive-side counter set UCS Manager keeps for one Ethernet endpoint (a blade's vNIC adapter port, an I/O Module uplink, or a fabric-interconnect server port) inside a UCS domain because comparing this average against totalBytesDeltaMax reveals whether receive traffic was fairly steady or dominated by a short burst. An average delta of 50 MB per sample alongside a max of 400 MB on this interface tells an admin one brief burst, not sustained load, drove the interval's total.