If you think about where the spine is and how it connects to the head then you'll start seeing problems with his pose. Consider these other things:
- His hips seem to be pointing one way while the position of his legs contradict this.
- His jaw is positioned up but his eyes don't seem to follow suit. (Yes the pupils are looking down but even the shape of the eyes seem to imply that they are positioned straight-on which contradicts the head's position).
So there are a lot of parts of his body which are well-drawn as separate elements but they don't seem to be moving together as one whole system. One body.
I think you're clearly talented but you need to draw more from life. Observe the human body in its natural state as well as the trees and other parts of nature.