Splitting strategy when betting behind someone else's hand

Monday, March 27, 2017

Splitting strategy when betting behind someone else's hand

In the splitting explained section of my blackjack page I go into the logic behind the “negative splits” - those hands that you split even though you still lose money in the long run, the crucial point being that you lose less by splitting than hitting or standing, whichever is the next best strategy.

To do a little recap on that: say you have 8/8 vs dealer 9. Nothing is positive here for the player. The EV numbers for split, hit and stand are -40%, -50% and -54% respectively (see the EV charts).

By hitting 8/8 (or 16) against dealer 9 we lose an average of 50%. Splitting loses 40%, and since the split gives us two starting cards of 8 against the dealer upcard, we can extrapolate that each of those starting cards of 8 gives us a 20% disadvantage, with the two of them yielding -40% combined. However, since two starting cards with a combined negative value of -40% (two 8s side by side) are still better than one starting total of 16 with a value of -50% (the two 8s together), basic strategy is to split.

However, what if there is someone back-betting (the “rider”) in the box we're playing? Casinos do not force the rider to double and split when the decision-making player (the “actor”) does so. If you're riding on my hand and we receive 8/8vs 9, I will split according to basic strategy.

What should you do?

As above, by splitting I cut my average loss from 50% (for hitting) to 40%. But you, as the rider, have the choice to split with me or choose one of the two 8s for your original bet, without making the additional bet. By splitting you sacrifice the same average amount as I do, 40%. By not putting out the extra bet, you only lose an average of 20%, which is fully half my average loss on that hand.

You can think about it this way: with that pair of 8s vs dealer 9, by choosing to not split with me you're basically saying to the dealer “please take away that top 8 and deal me a fresh card for free”. And there is no card that is not better: get an ace, 10 or 9 and we have a pat hand. Get a 2 or a 3 and we have a double. 4, 5, 6 or 7 give us 12, 13, 14 or 15, all of which are bad but not as bad as 16 - the 8 on the 8 is the worst possible card. By not joining me on the split, you're getting a free shot at a better card.

The same is obviously true for all those “negative” splits where the split loses us less. As the rider, never split with the acting player when the split is in this category.

Here is a full list of the splits that you should not join the acting player on:

• 2/2 vs 2 and 3

• 3/3 vs 2, 3 and 7

• 6/6 vs 2, 3 and 4

• 7/7 vs 2, 3 and 7

• 8/8 vs 8, 9, 10 and ace

• 9/9 vs 9.

(Details courtesy of the Wizard Of Odds.)

By correctly not putting out the extra bet with the acting player on the above hands you save 0.08% of house edge. If the actor is up against a typical 0.5% house edge your disadvantage falls to 0.42%, a reduction of around 20%. Although the negative splits are fairly rare you save a lot of money by not following the actor, which is why the improvement in the return is quite large.

The drawback? It's pretty much a golden rule to never trust your playing decisions to other players, as very few recreational players play basic strategy. As such, assuming you play basic strategy you will probably never find yourself in a “riding” situation unless you know for a fact that the actor is a basic strategist.

At the very least, you can explain this to any player who starts back-betting your hand, and then possibly enjoy the blank stares you get in return.

Permalink | Reply (0) |

0 Previous Comments

Post a Comment