What is significant about the fact that once again it is Karin who announce the arrival of the players?
Karin possesses the gift of imagination. Her ability to see and announce the players on the field is reflective of a capacity that is of this world, but not subjected to it. She has the imagination to envision that which is not there. A major idea in Kinsella's work is that there are elements of our being that exist outside of it. The truly transformative presence is one who can understand this, and embrace it. Unlike people like Mark, who are driven so much by material reality that they have lost imagination, and people like Richard, who have become so embittered with reality that they sacrificed imagination, Karin is gifted with it. She is a child, so there is a purity associated with her imagination to see what is not there. She gives life to what others would not understand. Her announcing the arrival of the players helps to enhance this. They appear to her and those who believe.
Karin's announcing and seeing the players helps to enhance the idea of spiritual identity or true religious understanding that is present in the text. It would seem that love of something, a pure and selfless love, is a type of spiritual religion. There is a selflessness involved when one believes in something with all of their being. Karin represents this in her imagination and ability to see what others perceive to not be so. Her possession of imagination and willingness to embrace something that others do not is where it is significant that she announces the arrival and presence of the players.