Google announced they have made a change that will affect the metrics reported in the Google Search Analytics reports. The change may increase the number of impressions and a drop in average position, although there was no actual change to your search engine rankings.
This is because it now “provides better accounting for results in lower positions“, meaning there will probably be more impressions beyond the second search page (position 21+).
Since the ‘position’ metric is an average, adding a lot more impressions at position 21+ will drag the average in that direction. By reporting the number of keywords at each position (see image), you would see that your actual ranking experience is probably unchanged.
This is actually good news: it means they are reporting more long-tail keywords!
The Excel chart in this article came from a free SEO Summary Report that shows the capabilities of the Analytics Edge Core Add-in and connector for Google Search.