To understand or get extra context about position changes in the SERP over a certain amount of time, the SERP (historic) overview in the Keyword Explorer has proven to be very useful.
Usually I'd take the SERP from before the drop / increase in position vs now. This makes any changes of keyword intent in the SERP (like 'new' Google snippets) and SEO efforts of competition very visual. Now you would have to do this comparison manually: creating a screenshot of two certain dates and comparing them side by side. A comparison mode between two or multiple dates in the (historic) SERP overview could be a nice extra feature.