I know there are probably as many opinions on what spotligth criteria there should be as there are players, but what are the current criteria for a mission to be spotlighted...if any?

Is it a required minimum number of players who have voted on the mission? A minimum average of 3 star rating? x number of days released? A max number of reviews per days since release with a minimum of 4 star average rating (underperforming missions with good reviews)?
Or simply a dev accidentally stumbling over a mission he thinks is pretty cool?

This is probably mostly a question for the devs, but I welcome any input.