Mr. Davis is a very different kind of teacher than Mr. Simet. Compare and contrast these two teachers.

Mr. Davis and Mr. Simet are like night and day. At first, the boys are looking forward to attending Mr. Davis's class; it'll be the first time that many of them will have had a male teacher. But they soon discover to their horror that Mr. Davis runs the class the same way as he runs the Mountain Bible Center: with a rod of iron. This is a man who will tolerate absolutely no nonsense whatsoever in class, and God help anyone who doesn't understand this. Even worse, Mr. Davis likes to humiliate his students. In one unpleasant incident, he makes the disabled kid Chris Coughlin stand up behind his desk; he then tells everyone in class—falsely—that Chris believes himself better than Jesus. And all this is because Chris, due to his developmental challenges, couldn't quite understand the task Mr. Davis had set him.
Mr. Simet's the exact opposite of Mr. Davis—thank goodness! He's helpful, inspiring, and kind to his students. It's Mr. Simet who encourages T.J. to start a swim team. The team will consist of all the high school misfits, those social outcasts bullied, sneered at, and rejected by jocks like Mike Barbour. This includes misfits such as Chris Coughlin, who now has a chance to come into his own in a nurturing, mutually-supportive environment. Where Mr. Davis is nasty and belittling to his students, Mr. Simet is encouraging, urging members of the swim team to improve their times at every meet, thus giving them a shot at the coveted letter jackets.