Re: feet movement during pitch
It looks to me like he is adjusting his feet because he is consciously putting himself in an awkward stance before the pitch, and then, when the ball comes in, his conscience effort stops focusing on his stance and starts to focus on the ball and his body is moving and adjusting itself for a more natural and comfortable stance unconsciously.
I think he needs to start in a more comfortable and balanced stance - not too much of anything. On the 1st two videos, his weight is prematurely on his back leg. In the 3rd video, I don't like his feet being that far apart. He needs to try to relax and just get comfortable and balanced. His weight shifts should start somewhere around the time of the arm motion of the pitcher.
Do get Jack's videos, both the Final Arc 2 and Swing Analysis.
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