If you look at all the good "skippy's" they all get their recoil set up HUGE. They appear to get so "open" that their belly-buttons face 2nd base!
I am not suggesting this IS the reason for faster "skippy's" but I can't find any other clue.
I noticed that the faster "vertically-challenged" pitchers out there that I have seen in my nation-wide travelling all seem to be skippy's.
That is true. The trail leg knee at open is often turned beyond third and more towards short and the shoe laces are not facing home which is a common teaching for the drag food.