Haha, shucks!
Ok, so in the screen shot you posted, those tets look too big to do the right thing 🙂
You'll need them to be much smaller (higher resolution tet mesh) to have enough degrees of freedom to let the mesh fit to the underlying muscles.
It's unlcear to me if setting the solver size to 5000 made the character about 1-2m tall. Basically the solver tells you what Ziva considers to be 1m.
So in this example, Ziva considers my sphere to be around 20cm in diameter.
Your solver should be roughly half the size of your dragon if you were to make it around 2m tall for instance.