I suppose the best person to answer that is Aulby himself.  As our own games evolve we all can make changes to help us "fix this" or "fix that" from time to time.

Over a bowler's life there are many things that stimulate changes; perhaps injuries, or arthritis, or loss of muscle strength over a period of years, or just the desire to be more consistent within our own scheme of goals, etc.

The nice thing about bowling is many types of people can excel.  Tall ones, short ones, skinny ones, and even "fluffy" ones. If one develops the ability to read ball reaction and (somewhat) repeat shots they can enjoy the game for decades.  There are also those who just do it for fun and don't stress over the previous night's league results.

I guess the point is our games can change over the years for a multitude of reasons.   

Mike wasn't a tall guy and did not seem to me to have a lot of ball speed. I would assume this type of pushaway was not only an aid to timing, but also helped him add a little ball speed due to a longer armswing.

Mike was a feel player as well as a streakie one...when he got the right feel in his swing, he struck a lot. Weber has made similar changes to his pushaway...it's all about controlling the swing & it's speed or timing for a better lack of words. It can be credited to changes in the game or an individual's body through age...or what they may think or feel they need to compete. What might not have worked yesterday might work today...if your not staying up with the game & it's changes you're losing.