Ehh, by separation, it would have been nice to have a light (@ low power) behind the subject; basically creating an outline around him, which would separate him from the background, rather than blending into it. Your edit definitely began to separate the camera right side of the image, but the camera left side still gets lost - nothing wrong with it at all, just a comment.
While this is more [LIght] than I would have expected for your shot, this is the idea (found via Google search): http://pacoromerophoto.com …04_Jamie_223_8x10_web.jpg
For your image, I prefer the small separation as depicted in the camera right of the image linked. I think it would have been nice if you could have got something similar on your subject's right side (camera left).