The diameter tolerance means it can be no higher or lower than .005"....that is the smoothness of a pool ball. Specifically because it is a sphere it works, the "elevation" change is the measure of smoothness b/c it is all from the exact center of the ball.

And the source you link has fairly glaring flaw; it doesn't actually use the tolerance limitations as mentioned above. It measures 3 random cue balls and simply uses those. So it is measuring a totally different thing that the "myth."

The limitation of a pool ball based on tolerance above is +/- 0.005". That equates to .01" in total from absolute max to absolute min. Over the entire size of the pool ball that is 0.44%. The corresponding measurement for earth (taken from your source) is .017%. So yes compared to the earth the allowable tolerance of a cueball is rougher than the surface of the earth. It doesn't mean that every cueball is roughter b/c many of them will be well under that tolerance and that is what your source measured.

And that is discounting the fact that Mt Everest and the Mariana's Trench are not right next to each other, and your source comments on that

Such a small area certainly doesn’t include things like Mount Everest and Mariana’s Trench in the same locale. And in many places, especially places like Louisiana, where I grew up, the Earth’s surface is very flat and smooth over this area size. Therefore, much of the Earth’s surface would be much smoother than a pool ball if it were shrunk down to the same size.