On my profile, I get a link like top 14% of this month; clicking on it, I am redirected to a reputation league display, where my month rank, change in rank, total reputation, and month reputation are displayed.
The value in change for me appears as "not previously ranked". I have been member for more than a year, but for those users who are member for less than a year, it is showing up the change value.
What is the criteria used here? Why the previous value is not showing up for me?