Change to the Ranking?

Today I noticed a big change in the ranking graphic on my dashboard. Since yesterday I have moved from the top of Cert 5 to the bottom of Cert 5, with no appreciable change in the numerical rank from the top.

The only explanation I can think of for this would be if thousands of lower ranked freelancers have been deleted, causing everybody else to be spaced further apart on the scale. That wouldn't be a bad thing, given the number of applicants that we have for most projects. Can anybody confirm that this has happened?