5" MB is porbably the mass bias is 5" from the bowler's VAL, vertical axis line (Sometimes called PAL,personal axis line). VAL is vertical line drawn thru the PAP, parallel to the vertical line drawn between fingers and down thru the middle of the thumb hole (Equivalent to longitude lines on the globe. Where that actually is is dependent on their PAP. Del's is obviously a much stronger drilling, with a 3 1/2" pin location. Because they have different pin placements, their MB location reflects different strengths, even though the number is the same. Del's is closer to a what is inaccurately called a 1:30/105 degree, while Bill's is closer to a leverage, but again, hard to tell, without more data.
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