Folks,
We have 3 different densities, core, filler, and coverstock, creating a single object, the ball. Those 3 different densities, 3 different chemicals/composites expand and contract at different rates. What makes them shrink and swell are temperature changes AND humidity changes. What accentuates those changes are the way those composites are treated from their formation at the factory, their drying and the environment in which they dry at the factory, the way they are treated by the driller (dull bits, fast drilling, not beveling holes, using too much super glue and the chemical in it, putting the pin too close to holes, etc.), the user storing in bad conditions (too hot, too much cold, too rapid change in temperature, too much humidity, too low a humidity, too rapid a change in the humidity) can all contribute to pressure built up in the different rates of expansion of these 3 basic components.
There's more places and environments in which something CAN go wrong than there are ones which can go right.
When one of them expands or contracts faster than the other two can accommodate that change, POW, Crack! $200 for a new drilled ball.
If you're smart, you won't trust to luck.
If you're lazy or rich, you'll ignore anyone's advice or suggestion.