If Petter Northug and Marcus Hellner had any doubts as to whether they’d be out of their element during the World Series of Poker in Las Vegas, the high temperatures in the triple digits over the weekend should serve to quash them. The two may be Olympic gold medalists, but they’re also unseasoned card-players. If they hope to fare well in the tournament, the Scandinavians will have to better old-school pros, new-school math-whizzes, and hundreds...