I didn't notice the ball till you said it, helm, but compared to the muscles it's hardly an offence.
As for crits, his shirt is flattening the crap out of his chest. Make it follow the contours of his pecs... all his muscles, for that matter, so that you don't lose so much volume. Also, avoid the tangent lines you've got in places for the shirt, it's not helping the whole volume issues as it makes the shirt look tattooed on rather than worn.
I dislike how his neck is wrinkly and how his face kinda melts into it, but that might just be personal preference.
You also seem to be missing an entire muscle between the pec and shoulder. Look at the man with the exposed ball, he has some peculiar muscle located where the straps of your man's shirt are.
One last thing, you seem to have a set way of drawing elbows when they're anything close to 90 degree bends viewed from the side. I could be wrong, but I believe that's a pattern you might want to break out of!
@Ryumaru (or anyone, really)
Thanks ("Very good gestures" :O), and I agree that my drawings lack structure, but I'm having a bitch of a time figuring out where to get started on that problem. Any chance you've got any tips?