At property level, when several site URLs appear in one result, the highest position is used. Page filters and aggregation scope affect interpretation. Smaller numbers indicate higher placement.
A change from three to eight does not mean every existing query lost rank. New queries, branded-search share, countries and devices can change the average.
Falling impressions alongside a worse average still do not establish a cause. Compare important query and page groups under matched conditions, then investigate demand, result composition and technical changes.