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 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 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 the endpoint this history row belongs to tells an admin one brief burst, not sustained load, drove the interval's total.