Oddsmakers set the NBA lines at TN sportsbooks based on a variety of factors. They look at the teams: who’s playing better and who holds home court. They look at the players: who’s playing better and who might be injured.
They set the lines trying to attract an equal amount of betting on each side. That way, they can earn a tidy profit from the vig and not have to sweat the outcome of the game.
That means big odds on big underdogs and heavy favorites laying a large amount of points in an effort to even things out.