I've noticed that some downloads that have been given 0-5 star ratings don't have an overall rating calculated, and likewise don't appear on the list of top downloads. For example, EverEternal WinterWorld 2, which was submitted a while ago, has quite a lot of downloads and ratings, but it still doesn't have an overall rating, even though some games submitted after it do.
What determines when/if a download gets an overall rating? Does a download have to have a certain number of comments/downloads?