Hiroki Kuroda pitching for the Yankees in June. He has a 3.17 E.R.A. and an 8-7 record this season.Credit...Richard Perry/The New York Times As a boy, he sneaked away from an abusive high school coach to gulp water from a polluted river. He saw some of his teammates, desperate with thirst, drink from a puddle, and he heard of others who would do so from a toilet. Now, 20 years on, Hiroki Kuroda sh