Tech, the farther reach back is just mainly for big distance. It sounds like you're probably still struggling with timing at those distance. Or were you throwing everything stand still? If so, you're not doing bad at all and sounds like you're making progress. I seen you mention a stand still, but I didn't know if you meant for all your drives. If you're throwing from a stand still, yeah that reach back will help you pull out maybe 320'-350'. If you're doing a run up then you're struggling with timing.
Can you describe a little more about "closing" your wrist. Is that the point at which you really tighten up your grip on the disc? Or is it a deliberate act of bending the wrist back toward your forearm? A friend of mine does this on every drive, but I thought I read somewhere that was counter-productive.
This is throwing back handed, I'm sure you understood that. Just clarifying. What you said that I underlined is correct. Yes, the point is to physically close the wrist, bending it toward your forearm. During this part of the pull through, it tucks the disc into your pec area if you follow the body positioning correctly. It's only counter-productive IF you don't allow your wrist to freely open when it comes to the end, it sort of acts as a spring, flinging the disc. "Snapping" the disc, like a towel. When the disc reaches the end of your throw, your wrist will be the last part that half "opens" meaning straightening out neutral with your wrist, due to the inertia of the disc coming through. That's where most people come to.
Now, part I mentioned above in my article about "fully opening" the wrist, bringing the wrist past the neutral position is a bit more complicated, and it changes most of your throw. The way you do this, is once the wrist starts to open, just as your forearm starts to open due to inertia, you physically use your muscles in opening it. So once the wrist comes to the neutral position, you physically push your wrist "fully" open, past neutral. It sounds easy, but it's harder than you'd imagine. The reason I stress this, is the same reason it was stressed to me. Because, once you learn to hit it, everything has to be changed with your throw to better facilitate the hit. Meaning, all the timing and everything you done before, probably won't work with the new "hit". But, this is for the good, don't let that scare you It just means you should really focus on this extension of your wrist. And, learning to do it, as once you build your throw around this, you'll ultimately build a much more powerful, snap oriented throw.