What is the author's style in The Challenge by Mario Vargas Llosa?

Although the narrator knows the characters very well, he provides little comment on them. While he gives surface information, such as where Leonidas lives and what the Gimp looks like, he never talks about his broken friendship with the Gimp or why there is tension between the Gimp and Justo. When Briceño sees Justo before the fight and expresses confidence in his ability to win, Julian merely says that Briceño seems to have decided to adopt this approach in talking to Justo; Julian is apparently not sure.