Well, it is actually a bit of both.

 

 Yes, the pin distance is a factor, but a good driller should know what pin position would be necessary, or usable, for building the reaction type you're looking for.

 

 Also, whether the ball is symmetric or asymmetric also plays a part. on an asymmetric ball, the distance from the pin to the cg doesn't mean as much as it can on a symmetric piece.

 

 Topweight also plays a part. With very low topweight on symmetric balls, pin distance from cg becomes less critical, due to the fact that any strange static weights that might have occured with a higher topweight are much less likely to occur, and much easier to compensate for.