The climax of the novel is the resolution of the victimization of the swimmers (receiving their letter jackets) and the arrest of Rich Marshall for the murder of T.J.'s father. The rising action has led up to a "showdown" for the team and for Alicia.
This crucial point prepares for the denoument of the swim team moving past their pain at the Hoopfest, where they show that they are able to compete at more than one level. With this self-confidence, their future is more sure. They have reached some type of redemption from their past victimization.
With the death of Mr. Jones, however, T.J. has been released from his need for revenge.
I think the climax is when TJ gets a Cutter letterman's jacket for the team. The whole novel has been leading up to his doing so, and when he finally does, he has succesfully done what he set out to do.
How did Tj's father get murdered?