Every team in baseball has a player who—while he might not be their best, or most famous, or most valuable guy—embodies what they are and where they're going better than anyone else.

In the National League East, Washington has Bryce Harper, who's so good no one knows how good he can be. Atlanta has Jason Heyward, who's so talented that everything he does manages to underwhelm. Philadelphia has the worn-down but still theoretically potent Chase Utley; Miami has the sub-anonymous Rob Brantly, whose name is known only by degenerate...