I'm sorry but I don't have a lot to add from the comments you've received so far. I think the reasons given are probably the ones that had you score lower in the challenge:
- no clear subject(s)
- bit too similar to other entries
- wide DOF so background and foreground compete for attention
For "frame-filling" shots (i.e. ones without a clear subject and even dof) to work, I like to see a more consistent item (in this case it would be leaves OR branches) so there's some unifying element. Here my eye jumps randomly over the image but there's no pattern(s) that satisfy.
If you have any questions or comments feel free to send me an email.
The focus is good, but there is too much in the shot. A close up on an area showing some of the detail in the branches/leaves might have been a better image. Still a nice job.
I'm guessing you were hoping to suggest a defiant remaining green leaf still clinging on with the weather getting colder? If so then one green leaf against a starker backdrop of tangled branches would have worked better.