Have you ever been on a blackjack table and accidentally hit a hard 14 with the dealer showing a 5 while playing basic strategy? Replay it in your mind, you bust on the King, dealer makes his 21 on a 6, the entire table gives you the death stare, curses your first born, all while mumbling under their breath, “Never hit on a hard 14 with the dealer showing a 5 idiot. That King was the dealer’s bust card. We all would have won.” Tough room.
First things first, those people have no idea what they are talking about. There is no such thing as “that was the dealer’s bust card.” The deck doesn’t know whether the dealer or the player is hitting or staying and the cards don’t change because of how someone plays their hand. The probabilities that guide basic strategy haven’t been altered because someone does not make the optimal play and theoretically the dealer still has the same likelihood of busting (in practice though, since the deck has a fixed amount of cards, the distribution of remaining cards changes the underlying probabilities of basic strategy. Card counting attempts to exploit this by identifying random deck distributions that happen to have a large amount of 10-value cards remaining).
The important thing to remember here is that basic strategy gives you the probabilistically best play given that the deck has a RANDOM DISTRIBUTION OF CARDS. That means that if the deck is not random, basic strategy might not be the optimal play. So what everyone should consider before baptize themselves in the holy waters of basic strategy is what it takes to make a deck random (and who controls what it takes to make a deck random).
To make a single deck random, the deck must be riffle shuffled about 7 times. Since suit doesn’t matter in blackjack, and K, Q, J, and 10 hold the same value, you actually need to shuffle a single deck less, about 4 times, to make it random. Most casino blackjack tables play with 6 or 8 decks at once which are shuffled together and played from a dealer’s shoe. In order to randomize a shoe of 8 decks, it takes about 12 riffle shuffles. Does your casino shuffle a shoe 12 times? Probably not. Most casinos shuffle a shoe 4 times, and that has some interesting implications when an entire table is playing basic strategy.
So let’s take a look at what happens to a shoe when the entire table is playing basic strategy. The first thing is that anyone that has a strong hand on their first two cards (17+) is instructed to stay, and their cards remain on the table until the deal is over. Players with weak hands play out their hands, and if they bust, the cards are removed from the table and placed in the discard shoe. This begins to create layers of cards in the shoe; clusters of low cards placed on the shoe first, followed by clusters of high cards that were left on the table. Since most casinos do not shuffle the shoe enough times, these layers loosely exist in the new shoe, and are further propagated when the entire table plays basic strategy (some people attempt to exploit this by using a technique called cluster counting).
Clustering of cards creates decks that are not random, which is one of the critical assumptions that basic strategy is built on. This creates opportunities for dealers to win/push more hands than basic strategy predicts. During a high cluster deal, a dealer is likely to have high cards to push, or even beat, the tables “strong” 19s and 20s. In the case where low card clusters are being dealt, a dealer will likely have a low up-card, a situation where basic strategy dictates to hit against until about 14. The thing is that since it’s a low cluster deck, the dealer has a better chance to make a hand! The player also has a better chance to make a hand, but basic strategy actually advises them not to try. INCONCIEVABLE!
Basic strategy is still by far the best way to reduce the house odds, but since decks are not completely random, there is certainly room for improvements in game play. For example, in high cluster deck situations, it may be worthwhile to split face cards, while in low cluster situations, taking another card to try to make a better hand may be your best bet. Playing this way may add a little bit more excitement to the rule-based approach of basic strategy as you’d be trying to exploit the rest of the table playing the basic strategy system. And if it pisses anyone off at your table, just turn to them and say “You fell victim to one of the classic blunders! The most famous is never get involved in a land war in Asia, but only slightly less well-known is this: never play basic strategy against a dealer when deck isn’t random!” I’d get a kick out of that if I heard that on a blackjack table.