I am not sure I can agree with the comments about the lack of contrast (even though they come from better photographers than I am). I think in terms of the post-processing it is alright.
Real problem is there is nothing overall of interest to the viewer, nothing to attract their gaze. Your title is "Over the River and Through the Woods", but where is the river? Where is the view or the path through the woods? Where does the path lead? You know, that sort of thing. Just nothing of interest or no story. Perhaps this problem exacerbated by the fact that the bridge doesn't stand out enough. When the entire photo is equally sharp there is nothing for the people's eyes to rest on.
Maybe this is partly a problem of post-processing after all. For example, when I do sharpening in PS, I mostly only do Smart Sharpen the main subject or whatever I want the viewer to focus on. So for example, for a in-camera JPEG file (at sharpness setting -2), I usually do 125% sharpening on the main subject (or whatever I want focus) and 25% for entire image, rather than just 150% for entire image. For your photo, I would sharpen the bridge (and the maybe the path) the most.
That said, I wouldn't take the ranking result too hard as it was an extremely competitive challenge. I've seen great photos rank low as well. It is certainly not a terrible photo, but it isn't a great one either...
Keep in mind that I've finished last place twice in the challenges, so I could be wrong.