I don't get it. If a swing is suppose to be free of muscle it should of one speed. so the feet matches up with the swing speed of the bowler. But, this article from USBC states differently.

 "You may have heard in the past, “Raise the ball to throw it faster.” Today, it's actually the opposite and what’s left out is that you need to match the swing with the footwork for consistency."

http://www.bowl.com/Source/Source_Home/Adjusting_Ball_Speed/

Here's the whole article without videos.

Adjusting Ball Speed
If you drop an object from different heights, it falls at different speeds, in theory. Gravity works the same way until it’s effected by wind resistance or terminal velocity. Your bowling swing and ball speed are the results of gravity but should be seen slightly different in terms of consistency.

You may have heard in the past, “Raise the ball to throw it faster.” Today, it's actually the opposite and what’s left out is that you need to match the swing with the footwork for consistency. Most would raise the ball and, without realizing, increase their ball speed by throwing it faster with their arm muscles. In bowling we should learn to speed up or slow down our ball speed by speeding up or slowing down our footwork. In this same lesson you’ve probably heard, “Keep a loose, free arm swing.” By raising or lowering the arm swing and not addressing the footwork, you’re doing it all wrong.

Balancing the arm swing and footwork tempos are essential to elite performance and ball speed adjustments are necessary in today’s game. By raising or lowering the ball in the stance and repositioning the feet, we’re only doing half the work.

By raising the ball and not changing the footwork, the arm swing has to pull the ball down from the top of the backswing to accelerate. You’re simply lengthening the distance the ball travels and not adjusting the footwork to match. A bowler gets out of time when this happens.

By lowering the ball and moving back on the approach the swing distance is shortened and the feet have room to accelerate. Try this: Take a few steps. Go back where you started and take the same number of steps faster, you end up further away. Using this combination of lower ball position and further stance from the foul line keeps the swing and feet in time. Now we can have a loose arm swing and faster ball speed because our feet did all the work.

 


 Lowering the ball in the stance and moving back on the approach increases ball speed


Now let’s throw the ball slower. Raise the ball in the stance and move up on the approach. The longer swing path matches the slower foot tempo.

Learn to adjust tempo by balancing the swing and footwork and by using the larger muscles in the legs you’ll be sure to keep a nice free swing.

 


Raise the ball and move up on the approach to decrease ball speed.
 

The whole theory behind raising the ball up was to allow the momentum of the down swing to help create a higher back swing with less muscle.  The theory is still valid, but it doesn't increase ball speed enough in a pure pendulum swing for higher rev players in todays environment.   More muscling, and later timing are the solutions of choice for most.   

 

Muscling is a relative term.  Anyone who is not a pure stroker ( a dying breed ) muscles to some extent.  You use muscles to accelerate the arm swing even if the swing feels relaxed. 

In a "true" pendulum system the time it takes to swing a complete cycle (from initial height, back and forth), is always the same.  A pendulum on a string that is swung back and forth has a natural frequency based on the weigh of the ball and the length of the string.  So if you release your child on a swing from a foot from the bottom or 3 feet from the bottom, the child will arrive back at the starting point at about the same time. (when just released, and not pushed.)

Now I know that a bowler and a ball isn't a perfect pendulum even with the lowest of muscle interaction.  And of course the rules of a pendulum system start to vary as you go more than 10 percent away from bottom center. 

But in general a longer, unmuscled swing will increase ball speed if the swing is started from a higher position. 

I personally think this article is full of inaccurate information as well.