The X-Files Season 6 Episode 19 The Unnatural ( Air Date 1999-04-25 ) Genre Mystery, Sci-Fi & Fantasy, Crime category. Overview "Mulder meets with Agent Arthur Dales' brother (also named Arthur) and is told a tale of a talented negro baseball player from Roswell, New Mexico in the 1940's who may have been an alien that ran away from his colony because of his love for the game.".