Without knowing your PAP it's hard to say what went wrong here. Keep in mind the Cruel core has maxed out specs so for the majority of bowlers you don't need to drill it strong.
I personally had mine drilled with a 5" pin above the fingers and a 4.5" MB/PSA. I kept mine at 1000 grit for the longer,heavier oil and I loved that piece!
The balance hole down by the thumb could be the issue too b/c it increases the dynamics of the core in that position.
Too many variables, not enough info. to make an appropriate suggestion. If it's at all possible please determine your personal specs - speed, rev rate, axis point, etc. and I will be able to help you if you want.
Get MOTIVated!
