As I stated in my last post the higher the FOC the more the vanes will dig into the air with the arrow nosediving more. Most of the traditional arrows are heavier and thus it causes more force to straighten the arrow out. If you have more down force on the front of the arrow it will make the vanes more effective. The bigger the vanes are the more surface area there is to work on the arrow. If an arrow has higher KE that means it has more speed thus meaning that there are more forces working to stabilize the arrow. Thats why the need for the bigger vanes. Also with shooting fingers. You get a less than perfect release and more fishtailing in return needing aditional stabilization.