Giving a professional athlete a nickname can be a fruitless endeavor if it is done hastily or without any serious thought. Only the ones that speak to an athlete’s character or persona ever seem to stick. And it helps if the name plays off pop culture.
Matt Harvey, the Mets’ ace pitcher, goes by the Dark Knight, another name for Batman. He takes it so seriously that he has his own logo, with his silhouette set against the iconic symbol of a bat, on his locker.
Some might consider it vain, but the nickname fits.