Ski jumpers don’t usually begin their careers at age 25. Nor do they progress from their first-ever jump all the way up to an Olympic-sized 90-meter hill in the course of one year. But that’s exactly what Australian cross-country skier Ben Sim is trying to do. There aren’t many athletes out there who have taken an approach like Sim’s and met with much success. But in the U.S., there’s one: Matt Dayton, who took up...