There’s a quiet renaissance happening in American distance running. At the IAAF World Cross Country Championships this year, the Americans beat the vaunted Kenyans, a team we haven’t bested since 1984. In 2012, Galen Rupp became the first American since 1964 to win a medal at 10,000 meters, and at the outdoor track and field world championships, Americans won medals in the men’s and women’s 800-meter and 1,500-meter races for the first time . . . ever. What made the differenc