Something that would be interesting to see is the gammon breakdown. A high gammon rate is probably a better indication of a successful blitz than the overall equity.
Below I've repeated the table that appeared at the end of this post, and added a red column for gammon percentage.
Each parenthetical value is the difference between that equity or percentage and the previous one.
- Position A (15pt) 1.093 ......... g = 51.1%
Position B (13pt) 1.117 (.024) g = 52.4% (1.3%)
Position C (11pt) 1.157 (.040) g = 54.1% (1.7%)
Position D ..(9pt) 1.304 (.157) g = 62.0% (7.9%)
Position E ..(7pt) 1.333 (.029) g = 63.8% (1.8%)
Note the big jump in both value and gammon percentage that occurs when the 11pt checkers, which are not in the zone (as I define it), are brought into the zone.
(Aside: Can any of the bots display the chances of CLOSING OUT your opponent? That would be an even better measure of blitzing potential.)
I can go along with that, and Henrik has some good ideas for compiling such data. It's extra work, though, and I feel certain we would be inevitably drawn to the same conclusion about the identification of zone checkers and their blitzing superiority to non-zone checkers.
The best type of position to look at is one where opponent is not on the bar yet, but he has a blot that you are thinking about attacking. The attacking play destroys your prime, so you have to choose which game plan to follow -- continue to play purely, hoping to build a prime, or go into attack mode, probably giving up on the prime.
I don't know if this example meets your intended criteria, but I grabbed it because it is easily at hand. If you back up my Position C and Position D one roll (and assume the cube has been turned), you can have the pre-C and pre-D positions below.
According to Snowie eval: On the left, Blue should point on the 4pt and make the 3pt (purely), while pointing on the 1pt is a -.162 whopper. By contrast, on the right, Blue should point on the 1pt (hitting a second checker), better than making the 4pt and 3pt by .003. The swing is .170.
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As I understand it, the traditional notion of checkers in the zone is that 10 or more checkers is enough to try a blitz. Fewer than 10 is not enough. (Obviously you have to weigh this with other considerations.) Is that your advice, Nack? How do you approach the "to blitz or not to blitz" decision?
That would be a whole book. :)
Clearly, 10 checkers in the zone is blitzier than 9. However, 11 is blitzier than 10, and 9 is blitzier than 8. There may be a bigger change from 9 to 10, but I don't think it's relatively monumental.
Comparing 62S-51 with 41T-62S-51, or comparing 52S-52 with 41T-52S-51, might lead one to conclude it is right to blitz with 9 in the zone but not 8 in the zone. Comparing other early game positions might lead one to conclude that it is right to blitz with 11 in the zone but not 10 in the zone. As I see it (consistent with the implication in your parenthetical phrase), much depends on the opponent's board strength and/or her blots/builders, and on the strength of the alternative candidate move.
Also, it is not always clear when to classify a move as a blitzing play. Consider 65R-43S-43 or 65R-43Z-43. Naturally, 8/5* is part of the play. If you also hit on the ace point (having only 8 checkers in the zone), does that mean you are making a blitzing play or are you hoping to get hit back less often, thereby protecting your lead in the race? Are these two ideas mutually exclusive? (Rhetorical questions.)
Nack