In a dramatic finish, Mystik Dan, under the guidance of jockey Brian Hernandez Jr., secured the victory in the 150th Kentucky Derby on Saturday. What Happened: The race, which took place at Churchill Downs in Louisville, Kentucky, saw Mystik Dan narrowly triumph over Sierra Leone and Forever Young in one of the Derby’s tightest finishes ever. The Associated Press reportedthat this is the 10th time in the Derby’s history that the race has been decided by a nose, the smallest margin in horse racing. Mystik Dan, an 18-1 shot, edged out Sierra Leone by a nose, with Forever Young another nose back …