Word Hero has a series of 'leagues', however its not clear what determines how someone qualifies for a promotion. Is it based on number of games played, some kind of moving average for the score or percentile, or something else?
If you go to
Help > Learn to Play > Player Ratings
in the app, it explains that it is based on a moving average of your last 50 scores, with some exceptions. The score ranges are subject to change according to the help file, but are, at the time of this writing: