Which is the most significant use of the word ‘crossover’ in the novel? Why?

I think this has to do with the crossover between basketball and life. Alexander uses basketball as an allegory for the game of life, suggesting that the lessons one learns on the court can apply to life off the court. He does this through Dad's "Basketball Rules" as well as aspects of the plot in general. Players on the court make mistakes or do incredible things, work together, sometimes win and sometimes lose, have to work hard and constantly be learning, and have to confront their assumptions about themselves. These all apply to life off the court as well, and Josh is the reader's guide for how this plays out.