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What PR difference will make this a practical drop?

Posted By: Chuck Bower
Date: Tuesday, 24 February 2026, at 4:04 p.m.

In Response To: What PR difference will make this a practical drop? (Bob Koca)

I used the "Fish Book" (Jacobs and Trice) tables. Those were created in the first year after Jellyfish's release, although I don't know that JF had anything to do with the MET's in the book. I think their tables assumed a gammon rate (G + BG) of 0.24, which is a bit lower than today's accepted value. Keep this in mind in my analysis below. Their tables were a function of Elo difference

The first question to ask is "will the better player, getting cubed, have a redouble to 8 if accepting?" The 200 Elo difference table indicates the answer is NO! The relevant scores are trailing 7a3a (31.5% MWC) and leading 3a7a (85.7%) if you want to do the math yourself. When I did I found the reboubling window doesn't open until White has 68.2% cGWC.

Thus the dead cube takepoint for White for the 2--> 4 cube has to be better than the 33.7% shown in Bob's rollout. Is it?

The relevant Table values (again, 200 Elo difference) are 7a5a (49.6%) plus the above values at 7a3a and 3a7a. Now doing the math (you can check my numbers) says White's takepoint is 33.4%. Since Bob's rollout is very close (but slightly higher) than this it's a tiny take.

I think the Elo to PR conversion is 33 pts of Elo to 1 point of PR. Thus the differnce of 200 Elo corresponds to a PR difference of 6. That's my answer; anything larger is a pass and anything smaller is a take.

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