"Top 15" is a bit unclear as well. I'm not sure if that means they'll just sort the list by "most rated" or "most popular" or if they'll aggregate all the scores and normalize them based on number of votes.
If it's just "highest average score" across the rating categories, then actually games with fewer votes have a higher chance of being rated highly. A game with only 1 vote (if that one vote is all 5 stars) could conceivably be the highest rated game.