Plus/minus tells how many points were scored in favor of BYU compared to how many were scored for the opposing team. For this game it tells you that Harding was on the court the most where BYU scored more points than San Diego. It gives you an idea of the players affect on both sides of the court. But there's 4 other players on the team so it's not the whole story. Finding a statistic for how good someone played defense is hard to do. This gives a small idea of how they played defensively.