When I first look at this image all I see is a regular picture of a lawn mower turned upside down. I think that might be why you didn't score higher. Voters look for more creativitity in challenges like this.
That aside, I think your image does have an interesting composition. The leading lines made by the stone path are really very nice. I think you gave a good idea of distortion, which works well in the upside down challenge. The focus is also very nice down by the lawn mower.
However, where you are lacking is in color. The colors seem very washed out. To me, it looks like it was the conditions under which you took the picture. Overcast skies, although they create nice, level lighting, also make for dully lit pictures that lack nice contrast and bold colors. However, it could just be the camera.