Sam was only a couple months into throwing the weight.  I'm not sure if I made it clear on the video so I'll over explain it here.  Just because you are strong doesn't mean manhandling the weight will make it go farther.  Pulling the ball on the way into single support, making the orbit smaller, will tend to result in bad throws.  I say tend to result in bad throws because some dudes are just too strong for it to matter.  ...Sam is not.