This was taken late in the day after a heavy rain.
Photography is all about the quality of light. Taken in the middle of the day in bright light or in the morning in the shade this image would not have been worth exposing. This image is all about emotion. When you look at this photograph you think about a similar moment that has been in your life. That is what makes a photograph successful. You connect with the moment. A fully inflated balloon would have ruined the feeling that is being evoked. More string would have been distracting. Nice balance to this image.