razor - thanks for the feedback. Are you saying he should strive for more 'direct propulsion' from the rear leg straight up through the core? That because of the 'sitting', he is breaking the chain in the drivetrain so to speak? Sorry, I'm not sure what the universal terminology is, so am just throwing various analogies out there!
His Korean pitching coach (a former successful pro pitcher in the KBL) taught him to 'sit'. I think this guy's idol was Hasegawa (rare to have a Korean idolize a Japanese player because of the history between the two countries, but just goes to show that sports can heal old wounds)??? He had a bunch of posters of him in his office, and Hasegawa SITS big-time. Not arguing, just explaining where that comes from.
Should he 'sit' earlier in the delivery, while the weight is still shifted mostly to the rear?
I think I understand what you're saying, and I think it also leads to that trailing foot DRAG that you'll see. I would rather see the rear foot PROPELLING directly off the front of the rubber. I've noticed that many of the hardest throwers around are NOT connected to the ground on the rear foot at release or VERY soon after.
here are Shiggy and the Unit....