This field is the average, as frozen at the moment this historical snapshot was taken, of the per-interval delta values for FCoE frames that failed to be transmitted correctly out this interface, taken across the retained collection history for this stats object. Admins watch this to separate a genuinely sustained problem from one noisy interval — if DeltaAvg for errorsTx on this interface is climbing, this is the transmit-side counterpart to errorsRx, rather than a one-off spike. For example, an average of 1 frames per interval sustained over many polling cycles points at a chronic issue rather than a one-time glitch.