One of the world’s most senior swimming coaches has raised serious doubts about the validity of the “unbelievable” performance of Ye Shiwen, the 16-year-old Chinese swimmer. John Leonard, the executive director of the World Swimming Coaches Association, yesterday compared Ye’s winning performance in the women’s 400m individual medley to Irish swimmer Michelle Smith, who won gold in the same event at the 1996 Atlanta Olympics but was banned from swimming for four years in 1998 for tampering with a urine sample. Smith, now De Bruin, always denied using performance enhancing drugs. Ye sent shock waves through her sport on Saturday...