It's not what the title says. I mean it's not a sports film, but it has a little influence of that. Instead the title should have been related to the word 'diary'. Because that plays a main part in this narration. This is the story of a homeless man who one day finds a diary in the trash. The diary of a young girl who had lost her mother and living with her abusing uncle. So on, it reveals her unpleasant life, but he finds some similarities with her. So he writes the replies, but since he doesn't who she is and where she lives, it goes straight into t... read the rest.
This movie is incredibly boring, and not very well made. No character development, shaky cam for no reason, long shots of nothing. There is never explained who the main character is. The kids recruiting him for fighting are vilified in the most amateurish way.
The plot is not so much about the fighting (very few scenes badly done), it is more about the homeless man, his environment and his delusions, using an imaginary friend to... talk to, I guess. I would go so far as to say the plot is really absent.