Marketplace – Like everybody else, bookmakers in Vegas know the Broncos are great and the Jaguars are awful. They don’t know what the final score will be. But they don’t have to predict the future to make money. In fact, Christopher Avery, a Harvard economist who published a widely-cited study about the NFL betting line, says the spread doesn’t reflect exactly how bookmakers expect the game to turn out. “The people who are setting the point spread are not trying to get the point spread right, in the sense of it’s the best guess about how the game will turn out,” he says. “They’re trying…