Blackjack First Base Penalty

For some time, we have been aware that it is better to sit at third base in single deck, face down games. (That is the seat to the far left at a Blackjack table.) Common sense tells us that we get to see more cards and can make better playing decisions. In an extreme case (seven players), the advantage difference between seats 6 and 7 is about 0.05%. You lose another .05% per seat as you move toward first base. However, the difference in advantages for a card counter between first and second seat is much worse. First seat can be as much as .16% worse than second seat. As this is a severe penalty, I decided to take a look. First, I looked at the winnings by true count. I created a chart which shows the winnings for first seat and second seat by true count. [link] The chart shows that the winnings are identical for all counts below 4. But, at a TC of 4, second seat does better. At 5-8, better and better. After that,. It evens out. OK, we now know that there is something about these particular counts that we should examine. I then decided to look at hand types. I took the winnings for the second seat and broke them up into an array of all possible two card hands vs. dealer up cards. This is an array of 330 values. I also created the same array for the second seat. I subtracted the second array from the first array and charted the remainders. The result is a combination surface area/contour chart that indicates the hands where the first seat has a problem. [link] Eureka! First seat has a serious problem with two tens against a 3, 4, 5 and 6. Tens vs. 6 is particularly severe. All other hand results are about the same. Common thinking would have expected many differences along the lines of the Illustrious 18.

So, we have a problem with 10’s against 3-6 at TC’s of 4-8. Guess what, the indexes for splitting tens at 3-6 are 4-8 (Hi-Lo.) So, why is there a major problem with splitting tens in seat one? Well, if you think about it, there is a quirk in seat one. Remember, we are playing SD, face down, seven seats. That means, two rounds. Only round two is important as that is where you are betting. To split tens, you must have two tens and the dealer must have a low card. If you are sitting at seat one, the only cards that you can see after the start of the round are two high cards and one low card. This means that the playing count will now be the count at the start of the round minus 1. If the round starts at a TC of +3, any seat has the possibility of splitting tens against a 3. That is, any seat except for seat one. Seat one cannot because the count will always be one less than the count at the start of the round or +2. 9% of the time, you will start round two at a true count of +3. 2.74% of the time, you will start at a true count of +4. This means that 6.26% of the time, every player has the possibility of splitting tens against a 6 in the second round, except for the player in seat one. (26% of all gain is in round two at a starting TC of +3 in this example.) The same holds for the other ten split opportunities, at reduced percentages. Therefore, seat one, and only seat one, has an automatic reduction in opportunity.

By the way, if you go through the same process between other seat pairs, you get the charts that you would expect. That is, the tens peak is muted and the other Illustrious 18 decisions start to poke out from the plane.

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