Late last February, Canadian Alex Harvey got the tag from his teammate Devon Kershaw to ski the second leg of the 4×10 k men’s relay at the Vancouver Olympic Games. Kershaw was having a bad day, and he’d dug his team into a hole—Harvey started out his race with a 30-second deficit to the leaders. The 22-year-old Quebec native fought as hard as he could, burying himself in an effort to chase down Norway, Sweden,...