Effect of coverstock, core and layout on ball motion[0]

[0] https://en.wikipedia.org/wiki/Bowling_ball#Effect_of_coverst...

It has to be asymmetrical because of the holes that will be drilled. And it is bullet shaped because of the "draft angles" of the mould (to make demolding easier)

tldr; "Core dynamics" and shapes change the hooking potential of a bowling ball

Here's a decent explainer:

https://youtu.be/qdY97ym_2Jc