Question on Soft DD indexes and basic strategy

[Automatic Monkey]

There's a question about soft DD strategy that has been puzzling me.

Using Basic Strategy, DD A4 vs. 4 but not A3 vs 4.

Now, when you have A3, 1 of 13 cards will give you 21, 1 of 13 cards will give you 20, 1 of 13 cards will give you 19, 1 of 13 cards will give you 18, 1 of 13 cards will give you 17, and 8 of 13 cards will leave you with a stiff.

And when you have A4, 1 of 13 cards will give you 21, 1 of 13 cards will give you 20, 1 of 13 cards will give you 19, 1 of 13 cards will give you 18, 1 of 13 cards will give you 17, and 8 of 13 cards will leave you with a stiff.

Now I can see how certain counts can create a difference in these two plays because some low cards are counted and not others. And in a SD game it can make a subtle difference due to removal effects but BS being what it is I can't see why there should be a difference to a BS player in a shoe game at all. Unless I'm overlooking something.

 

[The Mayor]

The answer is simple.

Recall that doubling means you can't draw another card.

With A-4 vs. 4, you really want to hit again if you draw an A, or 2, but you would be content to stand with any other card.

With A-3 vs. 4, you really want to hit again if you draw an A, 2, or 3, and you are content to stand with any other card.

Thus with an A-3 double, there are 50% more hands you wish you could draw again on (compared to an A-4), making the double that much weaker. Hence the count needs to be higher to justify doubling A-3, and you only double it against cards that are worse for the dealer.

The same general theme explains all the soft doubles A-2 through A-7.

Hope this helps.

--Mayor

 

[Automatic Monkey]

Thanks

for the explanation. That isn't quite intuitive.