OK Dusty asked for me to post my views on the subject. I have a couple one is the back foot ball trick.
I would like to say that when studing pitchers with great hip/shoulder seperation that do a couple things.
One thing they do is get on the toe or side of the ball of the photo.
Next they rotate the inner thigh in while they roll the ankle or ball over which creates alot of tension in the core and also gets hip/shoulder seperation like never before.
Look at the photo's below I will post of dan haren and also scott kazmir and if I can find more.
1st picture Dan Haren
Things to look at are the back photo on the ball of the foot.
Next Photo Dan Haren look at the back foot shoe laces down at landing.
This should be the focus of every pitcher in there mechanics because it opens the hips up past 60+ degrees which creates a big stretch in muscle
Dusty you told me in a Private message to put all the weight on the ball of my foot and when I did the roll over technique I got the most hip/shoulder seperation I have ever got even in dry throwing which when you take it to the mound you get a longger stride and It will become even better.
Now dusty I have never tryed to put my foot half on the rubber and half off I can kind see how that could work for some or just rolling over could work with the weight on ball of foot. Something that pitchers should try because you CAN increase your hip/shoulder seperation with practice of correct mechanics.
Last comment keep the glove more closed at plant so that you can get even more stretch in the core muscles.
Photo of Dan Haren and how he is closed.
Ok more photos of pitchers turning there inner leg down and in on purpose which creates more hip/shoulder seperation before landing.
Scott Kazmir Watch how the leg turns down and in before plant
Next pitcher of scott kazmir look how he is on ball of foot right before landing.
All the things I said look at every picture it should keep you busy.