In addition to stories that come in via the Boost Nomination Pilot, our internal curators also work from an algorithmically generated queue of stories. You can learn more about that over here: https://help.medium.com/hc/en-us/articles/360018677974

(Also, note that Boost Nomination Pilot participants can't actually Boost stories -- they can only nominate stories, which our curation team can select for Boost. It's an important distinction!)