Back Betting: Optimal Pair Splitting Strategy
By Arnold Snyder
(First published in Card Player, June 1999)
© 1999 Arnold Snyder
Many casinos outside the U.S., and a few inside, allow “back betting” by players who are not playing their own hands. Back betting is the practice of placing bets on the hands of other players at the table, whether or not you are seated at the table yourself.
Most casinos that allow back bets allow them only to the extent that the total amount bet on the hand does not exceed the table maximum. In other words, with a table maximum of $500, if the seated player is betting $100, back bets would be capped at $400.
Generally, most casinos that allow back bets also allow the seated player to make the strategy decisions on the hand. In practice, seated players will sometimes, but not always, defer this decision to a back bettor who has more money on the hand than the seated player.
Because pair splits and double downs require a player to put more money on the table, casinos that allow back betting usually must give back bettors the option of not placing more money on the table. This is due to practical considerations. If a seated player doubles or splits, and a back bettor on the hand doesn’t have the money, does the game stop? Does the casino tell the seated player he’s not allowed to double his bet since the back bettor can’t afford it?
With a pair split decision, if the back bettor does not put more money on the table, then the back bettor’s initial bet will all be played on one hand, and only the seated player’s money will be at risk on the second (and any third and fourth) split hands. This rule does allow back bettors to take advantage of some profitable opportunities not available to the seated player.
For example, when the seated player has a pair of eights versus a dealer high card, the back bettor can choose to play just one hand starting with a total of eight, instead of two. Obviously, an eight is not a great starting card when the dealer has a nine showing, so you don’t want to play two hands, but you’re also much better off starting with an eight than you are with a total of hard 16 (two eights unsplit).
The optimal back-betting split strategy will depend on whether the game is single-deck or multiple-deck, whether the dealer hits or stands on soft 17, whether or not doubling after splitting is allowed, and whether or not the European no-hole-card rule is in effect (i.e., dealer blackjack takes all on splits and doubles).
I’ll provide a down-and-dirty back betting pair-split strategy guide in this article, but if you are going to be playing extensively in back-betting games, then I’d advise you to get a copy of Stanford Wong’s Professional Blackjack. Wong never discusses back betting in his book, but his “Appendix E” charts show the expected value for every player hand versus every dealer upcard for most different rules and numbers of decks. With this information you can easily devise optimal back-betting strategy for any blackjack game you encounter.
These back-betting split strategies are often not intuitive, and they are quite different from regular pair splitting basic strategy. Let’s consider some of the back-betting strategies for pair splits in a shoe game, where the dealer stands on soft 17. Let’s also assume that the seated player is making all decisions and does not defer to you for advice. If the European no-hole-card rule is in effect, and if the seated player splits aces and tens against all dealer upcards, you should match his bet against all dealer upcards except the ten and ace.
If it seems crazy to you to split tens against sevens, eights and nines, you are right; you would win more money by keeping the hard 20 against every dealer up card. But if the seated player splits his tens, you too should put more money on the table. The reason is that, with the European no-hole-card rule, you’ve got a positive expectation on any hand that starts with a hard ten against every dealer up card except the ten and ace.
In other words, if you were controlling the hand, you would keep the twenty. But since you’re back betting, and the seated player has decided to split, you should go ahead and put more money on the table.
With a pair of nines, you would match his splits versus 2 through 8. With a pair of eights, you would match his splits versus 3 through 7 only. With sevens, match the splits only versus six. Never match the split when he splits a pair of sixes. If he’s stupid enough to split a pair of fours or fives, incredibly enough, you would match these splits versus a dealer six! If he splits twos or threes, match the splits only versus five and six.
A two-man team, consisting of a low-betting seated player and a high-betting back bettor, can use Wong’s charts to devise some very unique and advantageous split strategies. For example, consider the case of a pair of sevens versus a dealer nine. The best strategy for the seated player (hitting) has an expectation of -44%. This is a bad hand. If the seated player splits the sevens, however, and the back bettor doesn’t match the bet, the back bettor’s new starting total of hard 7 has an expectation of only -29%. So, if the seated player has a $10 bet, and the back bettor a $1000 bet, this is a very smart defensive play. ♠
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