Why hasn't anyone taught the changeup correctly?

I shouldn't be so absolute with my title. I'm sure someone out there is talking about some critical elements to the change. But, I have yet to hear a pitching coach discuss thoughts that seem so obvious. I'm guilty myself. I've always talked about what appear to be ancillary issues with respect to stealing MPH off the change.

Studies have been done that suggest that the best way to rob MPH from a pitch is to prevent the core from playing a significant role in the delivery.

Consider this. The legs and the core create the greatest forces available to throwing a ball with considerable velocity. Sure, it's the arm that throws the ball but it seems that the arm is a difficult variable to change with mechanics. You throw the way you throw. But, you can change some timing issues and some effort at the rubber and at foot strike that should be able to steal some MPH. All the while, giving the impression that you're throwing with maximum velocity.

If velocity truly comes from the kinetic link that starts at the toes and goes to the fingers, then the very middle of the link or the largest muscles should have the biggest say in how MPH are stolen. If you're attempting to change the pace of the pitch at the end of the delivery, it seems you're fighting an uphill battle.

Google how to throw a changeup? You'll find all the information on grips.

Do some research on your own. Look at ASMI and their research and you'll be convinced that the grip is an ancillary manner in which to steal MPH. Oh, I'm sure it helps throw the pitch. But, it doesn't appear to be the only variable involved. And logic says that it's certainly not the most important.