Nordic skiing doesn’t exactly come to mind when considering the X’s and O’s of sport. Those who don’t ski on Saturdays or Sundays might be familiar with football’s schematics. The arrows, the diagrams, the dense playbooks. Basketball has symbolism: X’s in the key, plays for a pick and roll, defensive shifts from zone to man-to-man coverage. The cross-country analog, and maybe this is a stretch, is the line-up for the 4 x (add a...