Lucky this is my point, you are basing your views off a single instance and your viewpoint only, you can't do this. Making the comment of seeing a greater retention could very well be a brand new bowling ball, this less wear or burn on the cover.
If you have shorter pin to CG balls, instead of distorting the core my drilling the holes deeper, merely move the pin 1/4" farther from pap and place the pin under or simply drill the pin out.
Keep in mind, there are no absolutes in drilling, we know the probabilities of safe layouts. Everything is going to be first & foremost surface and where & how the ball slows down...and understand, being left handed the surface or topography of the lane is different than on the right side...thus creating an illusionary ball motion in comparison to the right side.