I think that there can be a couple of moments where the climax can be seen.  I think that the moment in which Karin falls down and is about to take a fatal turn is a moment where the emotional and magically real moment for a climax becomes evident.  With so much around Ray at that moment such as the foreclosure of the farm and the criticism about the field, in general, Karin falling to the ground brings all of these issues to a point of convergence.  At this particular moment, Ray's life comes to a crashing halt, confronted with the magnitude of his daughter's life hanging in the balance.  When Doc Graham becomes the older Doc Graham and saves her life, the true power of the field, of the game, and the belief that Ray has held becomes evident.  At the moment of his most helpless, Ray has only his faith to hold on to and even before he has the chance to ask, Ray's faith is rewarded as Doc Graham saves Karin's life.  The morphing from the young Doc Graham to the older one is a climax in the point of the novel, demonstrating the redemptive power of the love of baseball and Ray's love and affinity for the field.  It is the demonstration that miracles can happen and that the love of baseball can be the field where this happens.  It is from this that Salinger demonstrates how the field can turn into a profit for Ray.  It is also from this moment where Ray is able to summon the courage to talk to his father.  The moment of Karin falling provides the climax moment, the point of intense action and tension, in order to give the resolution for these other moments to take place.