Pretty sure that's unofficial but it sounds about right. Her entire ranking was Luna and then Mantis if Luna was banned/taken with C&D as a third pick.
EDIT: Looks like it's based just on games played, not on how well you played. If you look at the Rocket Racoon rankings, the top 8th rocket player is gold 1 because he's put in 355 games as Rocket. If you look at Luna players by rank, Doki would be #9 while all the higher ranked Luna players have played less than half as many games as Luna as she has.