This is a good point but you need to understand that when triple extension occurs in the drive leg it is pushing the back hip forward which can easily cause early hip rotation. We do not want the hips to open until just before front foot strike so the rotation of the hips is more explosive and the pitcher can continue to build power through the stride. The only way to prevent the hips from opening early while the pitcher is trying to build power through the drive leg is to close the hips completely to the target or over-rotate them in the start position to prevent them from opening early during triple extension. Your point that this will cause a reaction to open early is valid but it can be remedied through holding the position and focusing on the force vector. This means when you lift your leg and pull your knee back towards your drive leg, you want to hold this position while you lead with your front hip and build momentum into the "Load" position which means you are lining up your force vector. This action will prevent the hips from flying open in reaction to the over-rotation at leg lift.

Does this make any sense?

I think I follow what you are saying – that it is the establishing and maintaining of the proper force vector until just before landing that prevents the hips from opening early, correct? Yes!

If I am talking about twisting the body it is only slightly. I am mainly talking about the lift leg. The lift leg can close off without having to twist the body or over rotate. This must occur if the pitcher is going to build power through triple extension and then convert that into hip to shoulder separation.

The lift leg path should not be the focus during the stride. It should be put into position at leg lift but once the stride begins it must follow the lead of the front hip. This means if the pitcher does not build momentum effectively during the stride phase and the path of the lift leg is the main focus then the lift leg will look more like Evans. If the pitcher is able to build speed early with the front hip leading and the drive leg closed off and then continue into triple extension, the lift leg will look more like Lincecum and the other hard throwers. 

The problem here is that pitching is an explosive movement. This means we can not take away from the ballistics of the movement by making the lift leg the main focus of the stride. When the lift leg becomes the main focus we see young pitchers stop accelerating their momentum through the stride because they are focused on the lift leg path. This will have a major impact on velocity because it kills the entire ballistics of an explosive delivery.

Coach, I have a great drill for this coming out in my beginners guide. I use a harness and a sled to train the "Load" position and the force vector. I feel that a drive or pull of the sled instead of a push of the hips creates a movement more specific to the actually pitching delivery. I have found that it trains the force vector more naturally this way.