There currently is such a system that states your score. (As shown below is the online leaderboard)
Though it does not display in online, when you are to set a local highscore it displays your rank, name, and score within the device. (As shown below when playing offline)
I am sorry if I'm just not understanding but the display of a player's current rank as they play through the game is already implemented except when online, as I am learning how to work with APIs.