Let me clarify the gradient line for you guys:  Basically its just a line draw from the bowler's PAP to the PSA as a guide to where to place a weight hole.  The general rule applies that the closer to the PSA the weight hole is placed the more the intermediate and total differential are increased.  That being said, let's say  I would like to create a weight hole 1" from the PSA but the drilled ball has 0.5 side and I don't want to take that much side weight out of the ball, I would bring the hole closer to the center of the grip still one inch from the PSA of the bowling ball.  Same effect, different amount of static weights taken out.  The gradient line is a simplification on this for pro shop guys so they have an easier guide of the relationship between weight hole placement and effect.

If there are any other questions let me know.

Paul