How can anyone be 6'3 165? I don't understand. I mean it's really hard to imagine someone like that, I've probably seen in the far past one or two guys like that but they could barely stand on their feet and were slow and uncoordinated as fuck.
By the way - I've rarely seen people use their hips properly when they do backwards med ball tosses. The VAST majority of them use their arms with the hips barely doing any work. Of all the people I know, I really really use the hips. Which is weird because of all the people I know, I don't use the hips at all on the powerclean. Very interesting how this is so different.
Well you feel like you use your hips... but how do you know that? And who are the vast majority. These NFL guys toss the 12lb ball almost 30 yards. That's impossible if you only use arms...
Try to take the word "only" less literal than you currently are taking it. Of course they use their hips, it's not 100% arms and 0% hips, just like in my case it isn't 0% arms and 100% hips. How do I know that? Watching video and feeling the complete extension/hyperextension. Some people end their hip extension movement and then they still continue moving their arms, and then release the med ball at the moment their arms stop moving. So it's a sequence where the hips aren't doing anything and if anything, they just added some "momentum" to the arms or whatever (try not to take this literal again, you know very well what I mean). The difference in timing might be (very) small, but it's there, and it makes a difference.
In my case, and a few other cases of a friend I was training with, the timing is perfect and it looks like an Olympic lift, a continuous movement where the medball is "launched" by the hips through the hands, but most of the time what I see is this lack of timing and the overuse of the arms to throw the ball.