Well, before I bore the life out of someone, I usually lead with, "Do you really want to know the answer to that? Because I do know..." Then I'll go with the simplest explanation I can think of, something like, that's the top of the ball. If they want more info then most people know I'm happy to elaborate. I probably wouldn't mention weightblocks to people who don't bowl, as it tends to invite more questions than it answers, in my experience.
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Reporting from England