ERZURUM, Turkey — For elite skiers under the age of 20, the FIS Junior World Championships are a focal point of the previous year’s training. No matter the national team, an athlete’s success at World Juniors causes elated finish-line celebrations, as it confirms he can ski as fast, or perhaps faster, than he ever thought possible. The freestyle sprint, the opening events of the 2012 championships at Kindalli Nordic Ski Center, was no exception....