Note how Simon's right femur/pelvis is turned further back and driving further targetward while left leg steps behind further targetward and less impeded by frontside/pelvis.
View attachment 318167
As you both know I got stuck on this for months. For me I think it had something to do with (1) wanting to keep my eyes on the target, which would (and still does to an extent) pull my whole posture too open too early/out of sequence and (2) failing to connect the pump with the legs. I have a suggestion.
TL;DR: In the end it's basically just "do more battering ram in your pump."
NDK, I started to make more progress with this recently returning to something closer to the "cradle" pump like you have. I'll break down what is working for me and try to show it.
I've been using Battering Ram kinetics in my setup and focused on letting the backswing help feel like it pulls my front leg more closed/femur back as I started my move forward. I realized I could also search for better backswing depth and posture because suddenly my front hip wasn't blocking the range of motion. Here's a shot a session or two into working on it. This swing isn't perfect but serves the current point.
Notice (left to right; SW has me standing taller than you which is now clearly working better for my body, so just focus on the actions I'm emphasizing):
- I am balanced on the front leg when I do the baby elbow pump.
- (1) As my elbow pump comes back braced against my rear leg, then (2) the front leg/hip/knee/pelvis is coming back with it. The femur and front knee come back away from the target with the little "walk."
If you don't find the connection between the upper and lower body in this part like Battering Ram, you are probably forcing something!
- As pressure loads on the front foot, I'm relaxed so my body doesn't open that hip (so it more naturally internally rotates). Notice this is letting me get more of my mAss leading me into the plant without forcing it. Difference between me and the Ram is part camera angle and part just staying more closed off with the pump.
Simon is doing this but it's not always easy to see when he uses a tiny pump. Look closely
Slowed/powered down with pump:
This was super annoying to fix but IMO worth it. Effort went down/peak distance went up and I started to have more consistent control of landing in the plant and my release angles. Now I can tell right away if my front hip isn't coming back naturally per above because the old way feels like crap. IMHO it is important to "abort" the swing immediately if it doesn't happen correctly, then try again. After ~3 weeks I almost don't need to pay attention to it anymore, but it's now part of my pre-shot routine since it's been a weak point in my throws.