The best place to find addition speed is leg drive and hip mechanics. Without those a pitcher is all arms and shoulders.
I've been watching the following videos and still feel the opening and closing is directly related to the arms and legs. Hard to explain it, but the extension opens the torso,...
and I feel my body being closed by pulling against my arms and drag leg.
During an overhand throw, I get open with a hop, then push against the ground with the back leg and pull the hips/torso with the stride leg snapping open/forward.
Can someone give a brief summary of overlap as used here on the boards with respect to fastpitch/IR. I've seen its usage, particularly by in Java's threads, but to paraphrase of Inigo Montoya, I'm not sure the word means what I think it means. ; )
Thanks