I didn’t vote in the Rule of Thirds Challenge so this is the first time I’ve looked at your image. My first impression is that the image is rather busy and I had to search to find the main subject. Probably what hurts this image the most score wise is that the subject isn’t isolated very well. The two people behind the skaterboarder really diminish the impact of the main subject. However, when you are shooting street shots, it is hard to control the environment around you. The focus on the skater also looks a little soft. Your shutter speed looks more than fast enough for the action in the image, so I’m left to wonder if it was a focusing issue or did you forget to sharpen after downsizing the image for the challenge. If it was the later, try a little Unsharp Mask with a radius of about 1 after downsizing.
Overall, you captured the action of the skateboarder very well and I love the fact that the colors in the image look very realistic. You found a great shooting location and I hope you go back and keep shooting.
Feel free to PM me if you have any questions regarding this critique.
Skyline, Horizon, foreground. Great use of rule of thirds. As for the photograph well it's a little cluttered there's so much going on. I mean getting the skater in there is great timining except the people behind him are distracting. Good job though.