In my opinion, rank is not important(although that is good if we have more in that league), what the community want is the more number of top curators having Unique Author Ratio more than 0.6 or so. The community only has one curator in that zone at this time. The community and the new users feel comfortable with curators having Unique Author Ratio more than 0.6. Curating more unique authors also makes the curation engagement dynamic.