Louie,
In drilling asymmetric balls, many more factors come into play.
1. 5" pin on a Track asymmetric put the core into an end-over-end "looK".
2. MB position plays a much more important role in asymmetric layouts than in symmetric ones. You di dnot indicate where it is.
3. Assuming your "thumbed" release has different specs (tilt, PAP, rotation, etc) than your thumbless one, is this ball drilled for that. You had said you had not been doing that. The GP2 is a touchy and expensive experiment with which to return to "normalcy".
All this will affect the ball's performance. I'd be willing to bet that more than one of these factors is off for you and your ball.
Tenpinspro and Excaliber, among others, can be of much more help.
--------------------
Bowling: Just like hand grenades and horse shoes, you only have to get close.
Life: Deal with what is.