FOXBOROUGH — The first adjustment was figuring out the helmet, shoulder pads, and the rest of the football player’s occupational armor. “It was awkward,” Nate Ebner recalled. “I had to make sure I did everything right the first time I was putting them on.”

There are no plastic hats in rugby, where the leather scrum cap is a 19th-century vestige. Until Ebner walked into the Ohio State locker room in 2009, he’d been a fly half for Uncle Sam’s junior team and for the Buckeye club squad. Suddenly he had a facemask, a playbook, and a new job description.