Those are some great shots red hot.
HYP i drew it out on paper, and i see the path you talk about .
However, when i look at the front veiw of your clips, the back hip, goes in a straight line, in the coil foward.
the front hip closes a bit, more so in some mleaguers than others, then the front hip begins to open, with a severe pinch on the front side, just like it had on the backside, it hits this strong resistance and the front hip deflects back. The back side is releasing, by then, because i can see the rear foot, being dragged foward. ( i get lost on how the back hip can keep resistance with nothing to push against, so it must be from just clenching the muscles in the hip area that keeps the pressure in this area).
Bottom line is, the rear hip goes in a lineal direction , the front side rotates and counter rotates.
Front side views, and some REAR side views, and more top views, would be good to look at. I am also interested in the ANGLE of the hips during all of the swing.
OK, let me explain what it is I believe you are seeing.
Yes, when the rear hip coils the front hip will close off. The rear hip is moving in one direction the front hip will move in the other. So, when the rear hip is coiling back around the front hip is closing some but the rear femur has not started to work under yet. If you are coiling and moving out with this coil. The rear hip is moving away from the rear foot. Lengthening the rear leg some. Now, as the rear hip gets coiled past the quarter turn phase it is now moving in the same direction but is headed back towards the "infield" or plate from inside. Now, the femur starts to work under the rear hip and that forces the pelvis open, which moves the front hip back and around.
Some MLB hitters coil and don't move out while some coil and move out.
There is a clip of Pujols from behind him that shows this. I will try to find it.
Why does the front side rotate back? In some MLB hitters that have a high leg kick. The pelvis starts to open prior to the front foot getting down. How does that happen if the front foot is not on the ground?