Is he staked to the ground with the bowling ball on his collar too? He looks on the this side but not emaciated IMO... of course the pic is too far away to tell with any accuracy. I thought you said he was in a tiny cage?
8\ Not emaciated. Goats are just built that way. As far as the ball, goats are strong (coming from someone who used to own goats and had to wrastle them to trim their feet >.<) I'm sure that barely hinders him any movement.
Probably just keeps him from running away or quite possibly he could have been a fence jumper. The collar isn't even tight, and that's the natural headset for a goat.
That pic is almost exactely how I chained my goat when I first got her. Her chain was about 2 feet or so longer, but same concept. And I used a cinder block. She could drag the block to move around a bit but it was too heavy for her to take off with in. Didn't keep her on it as long as your saying though, just enough to train her to stay. You can't fence goats, you have to teach them that being in the fence is a good life. When I tried to tie her to a tree she got tangled and almost strangled herself daily. The short chain tied to a weight is about the best way to do it.