The bodily proportions could be better (upper body and lower body should be roughly equal in height for an adult), but I think its the arms that bother me most. What gesture do you want him to make? The head and right arm suggest 'who else wants to take me on?', but having him extending his left arm, as if he's punching at the same time, seems out of place.
It's supposed to be like an arm-pump in victory, except the stance and everything being caught when the arm is fully extended thus the punching look.
It appears that you are still thinking of anatomy, and drawing in general, as a flat 2D world. It's good to know that you realized the need for foreshortening on the hand and leg, but the muscles on the chest do not follow with this. They kinda look tattoo'd on, rather than physically being there. This also isn't helped by the fact you are using lines to describe areas of the body which display subtle light/colour changes in reality.
Take the following as an example:
The question you should ask yourself is: do you see any or harsh heavy lines to indicate the anatomy?
Also heads need work
Okay, so based off of what I see from all your drawings and all these directions you're getting pulled into, its looking like you want to put a dynamic figure in a space.
So what I suggest is practicing a bit of perspective drawing, 2 points then 3 points, make a couple drawings of that or until you think you got it. Post some results so we know to what extent you know about it. It could be a buncha rectangles and spheres or any simple shape.
After you do that, instead of using posemaniacs for now, see if you can find a mannequin (small ones are available at art stores) or a skeleton that you can pose, and some grid paper from the office store. You're going to use what you learned in perspective drawing to draw a stick figure. Put the mannequin on top of the sheet of grid paper, with the grid paper lined up diagonally to you. Set up a perspective grid on a regular sheet of paper, and for every joint you see on the mannequin (which you set up either standing or posing) place a circle on the page. Think about x,y,z of where that circle is in the picture. Connect the circles/points as you would for bones.
What I hope you'd benefit from is learning how things translate from 3d to 2d, and hopefully you can nail some basic proportions while you're at it. Paying attention to how far each joint is from each other may yield results.