If you are going to argue that my example is a "flawed" experiment noting that the core shapes are only similar in numbers but ultimately different, then you are saying that core shape matters in the equation. If core shape matters in any factor of the equation, given your argument with me, we measure the core relation after construction of the ball with the x y and z axis and the differences of them, and show that in Rg and differential (and sometimes intermediate differential) to quantify the core with numbers. The thing is, I can look at a core shape and get a rough idea of it's characteristics based on symmetry and comparing to previously released balls with similar characteristics, but what I CAN'T see, is the density of that said core, or see what materials were used to construct the core. I can't see how dense a flip block is, I can't see how dense the main body of the core is compared to the flip blocks, or be able to tell how much it weighs by looking at it. The weight of the core will also determine the amount and density of filler material needed to create a desired weight of a ball. Rg helps give us an idea of the core being very center heavy or being cover heavy. So, since my test is "flawed" because of it using two different cored balls, and Rg is one of the telling factors of the density of core to filler material to cover weight of a ball, then Rg matters, because it shows the numerical differences of different cores.