When drilling into the ball you begin changing the core numbers, rg, diff, and the int diff.

Usually with pin up layouts you increase the int diff the most because you are taking out a lot of the side of the core creating more asymmetry. From the experience I have had using blueprint software to try out different reactions in layouts, weight hole locations etc etc I found that putting the pin up and having the psa in the thumb hole was the most aggressive location for increasing the int diff possible with out adding a weight hole. In terms of the amount it will increase the balls internal diff numbers vs other locations

The only reason I tried this was for a friend I drill for who doesn't like x-hole in his equipment period. So I was trying to find the best options no matter how minimal and non effective in the end that I could for drilling a ball for him since an x-hole was not an option.

The asymmetric core bowling balls burn off energy faster is how it is usually always explained and gives me a good visual of that compared to something more symmetric.

I would focus more on the actual weight hole location and affect with the drilling more then just the psa location and the x-hole being on it.  When you drill the ball prior to a weight hole the psa moves towards the thumb hole.....then when you drill a weight hole in a different location the psa will then move again towards the added weight hole. The bigger/deeper the hole the more it will shift. The pin also moves with the psa equally away from holes that are drilled.

They could have drilled the ball that way for any number of reasons. The end results aren't always as much as people think or expect to see on the lanes. The numbers of the core may change what seems like large amounts, but that is deceiving when applied to real world applications on the lanes.

If you get time try out the free trial of blueprint software......it takes a few minutes to figure out and get going but it will give you hours of entertainment and some better understanding of what is happening to a bowling ball when being drilled.

http://blueprintbowling.com/

Here is the core specs after drilling the ball 30 x 5" x 40

You can see the change in the core numbers after drilling along with the original pin and psa locations and where they shifted after drilling.

This one is the earlier 30 x 5" x 50 layout again with a large 1" x 3.5" deep x-hole added down near the thumb.

The weight hole is located 3.5" right of the center grip line and 2.5 down.

You can see the shift in the pin and psa along with the change in the core numbers.

THANKS!

 Mr. Hamlin,

  Yes, it is a mb creared by a "knob" rather than simply by shape or density placement.

Thanks again guys.

 Sometimes the wealth of knowledge available here just amazes me.