I guess it's more of the quantity of comments you have.
My guess would be: hubpages has this "ratio" designated for each level. Though, I'm not really sure about the validity of this. It may be based on the number of hubs you published, the number of days you are in hubpages or so.
This means that, regardless, you must keep on posting helpful comments in order to maintain your accolade level (or better yet, increase it).