A match play decision

[Simborg]

It's 2-away, 2-away (actually, it was 7-7 in a match to 9). This was in the finals of our weekly Chicago club tournament. Black is on roll. What is the proper cube action?






I was black, and I thought I had an edge here. At this score, you are supposed to double even if you are only 51 percent to win. So I doubled, and to my surprise, my opponent dropped. That was a big blunder for him to drop. With me now leading 8-7 he must win 2 games in a row or win a gammon, so his match equity is 30 percent. He should take this cube if he wins more than 30 percent. As you can see from the Snowie eval, he is 43 percent, so he gave up 13 percent by dropping.

I did win the match, by the way.

[LuvChild]

"At this score, you are supposed to double even if you are only 51 percent to win."

If this is true, why wasn't the cube turned (by either of you) before this point? (I'm assuming you haven't been dancing on the bar too long, if at all...) It seems as though offering the cube with only the slightest advantage is giving up match equity in a similar but opposite fashion as your opponent who dropped.

Am I wrong here?

Thanks

[Simborg]

You are not wrong, and you raise a very good point. It is likely that either white or black should have cubed before this. However, I was black in this game, and for quite a while I was in the kind of position where I might well win a gammon. On white's last roll right before this, he made his anchor in my inner board and hit me. Had he not rolled so well, I would played on for a gammon. One reason I can do this is, if things go poorly, as they did in this case, I could still have an edge and double.

I am not unhappy with the outcome, as I did get a drop from my opponent and became a 70 percent favorite to win as a result. Had I not doubled, I was only a 56% favorite to win the game, and it's a game I could have easily lost, particularly if I came in with a 1 instead of a 3.