Saturday, December 6, 2008

Should Kings be Folded Preflop?

Given the action of one of the final hands of WNP’s action, the debate rages on about whether or not it is correct to ever fold Kings pre-flop. Ryan’s Kings vs. Martin’s Aces played out I believe as follows:

Mike limps, Woody limps, I limp, Martin limps from the late position, Ryan raises to 15, blinds fold, Mike calls, Woody calls, I call, Martin goes all in for about 700 +, Ryan calls for about 560 chips, everyone else folds.

Although there was some dead money in the pot, Martin’s bet size and Ryan’s decision on whether or not to call was close to a 1:1 decision, i.e. the pot was laying Ryan only sufficient odds to call if Ryan was convinced that he was in a coin flip or better decision. If Ryan believed he was in a better than a coin flip situation he should call, otherwise he should fold.

Though we have to use some assumptions and logic in this decision, mathematically, we can determine if Ryan’s decision was the correct decision in this situation, and if we change the player’s name from Martin to another player we can simply alter the likelihood of the nearly 3x buyin shove with a different distribution of the ranges of hands that the player might hold.

With nearly a 3x buyin shove, we can narrow the range down pretty tightly. Martin’s range, or for that matter any player’s range, is as follows:

Air: Martin may be on tilt, spaced out, needs to go home, or just feels like gambling. Martin has to my knowledge never demonstrated this type of behavior on a shove of this magnitude, but let’s say it is possible and extend the probability of an air hand at 2%. Let’s also at least narrow down “air” to a suited connector or 1 gapper, and say that true air has a near zero percent probability.

JJ or QQ Very unlikely at a nearly 700+ chip shove especially as I am in the hand (potentially) and I have Martin covered. Martin also has a history of set mining with big pair hands. Let’s extend the probability of Martin holding this type of hand at 4%, which I think is an overestimate but let’s go with it.

AK Again, very unlikely given the reason’s stated above. Let’s give AK a 4% likelihood.

KK Extremely unlikely, given that Ryan has 2 Kings in his hand. Let’s extend this possibility as statistically insignificant.

AA The only other logical hand. Let’s extend this possibility at 90% given that Martin is the player and given the set of circumstances surrounding this hand.

Ryan’s probability of winning this hand by calling Martin’s shove is as follows:

75% win rate against air hands @ 2% probability = .015
80% win rate against QQ and JJ hands @4% probability = .032
70% win rate against AK hands @ 4% probability = .028
20% win rate against AA hands @90% probability = .180


If the forecasted probabilities of the given hand ranges are accurate,
Ryan will win the hand approximately 25.5% of the time.

The tipping point as to whether to call or fold an all in shove with KK in a deep stacked hand (assuming one big shove vs. a raise re-raise situation) is determined by the likelihood of the villain holding a hand other than AA. Leaving air at 2% and assigning an equal probability to either having an underpair or AK, the decision will be a break even proposition at the following probabilities:

75% win rate against air hands @ 2% probability = .015
80% win rate against QQ and JJ hands @24% probability = .192
70% win rate against AK hands @ 24% probability = .192
20% win rate against AA hands @50% probability = .100

Win rate = .499

Replacing Martin with another villain, and assuming the pot is only laying you effectively 1:1 odds to call, the decision as to whether or not to call with KK is simply based upon the likelihood of the villain holding AA being greater than or less than 50%. If you believe that the villain’s likelihood of holding AA is greater than 50%, you should fold, if you believe it is less than 50% you should call.

To be fair to Ryan, he did point out that he had been raising a number or pots and that it was very unlikely that Martin put him on KK. At the time, I believed Ryan’s decision was a tough one that could have gone either way. With the benefit of a couple day’s rest and some analysis, I would be very surprised if anyone would say that the likelihood of Martin holding a hand other than AA was greater than 50%. Thus, the correct decision in this given set of circumstances was a fold with extra heroics if Ryan had been able to fold the KK hand face up for the table to see.