Scott,
I think spin times are too easy to fudge or misinterpret, to be kind. The last 10 asymmetric Track balls, made by the old Track company all had spin times around 5 seconds. Yet MoRich balls all have/had significantly stronger Mass bias strengths, and significanty stronger breakpoints, that I have seen.
When Mo wrote the article in BTM around 2000 or hereabouts, he used balls at 2000 grit Abralon for consistency. Other than that, I don't know if everyone does the test the same way or even follows the directions. Thus, I'm not sure, I really wonder how significant the spin time really is. MB strength varies with drilling, pin location, and bowler's release and surface and oil amount, etc. There are so many variables in this equation.
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"None are so blind as those who will not see."