Pot-Limit Omaha: The Flush-Board Continuation-Bet Percentage

Flush-board flops (three cards all of the same suit, making a flush possible) present an interesting situation in pot-limit Omaha (PLO), particularly in pots contested heads up on the flop.
Here’s a typical situation: It’s a $1-$2 shorthanded PLO game online (six-max, six-handed) with $200 stacks. The button opens with a raise to $7, and only the big blind calls. Their holecards are irrelevant.
The flop comes J♥ 6♥ 2♥. The big blind checks, and the button bets $8, or roughly half the pot.
Here’s the thing: This is an easy continuation-bet (c-bet) situation for the button, as most of the time, the big blind will simply fold to the bet whenever he doesn’t have a flush. This is particularly true of weaker players, who are typical in smaller-stakes games.
That said, this is also an easy check-raise situation for the big blind. For the most part, when the button bets, he either has a flush or he doesn’t; if the button doesn’t have a flush, he generally will fold to a check-raise. The key is that when most players follow through with a continuation-bet on a flush-board flop, they generally will have air far more often than they will have a flush.
In a poker article several years ago, Brian Alspach noted that the probability of the button having a flush in this situation is 20.9 percent, assuming that his cards are random, and 42.2 percent when assuming that his hand is double-suited. My best guess — assuming that a player will generally want to be at least single-suited to come in with a raise — is that the probability is closer to 30 percent than either 20 percent or 40 percent.
However, the average c-bet percentage for a typical player is in the 50 percent to 70 percent range — well above the probability that he will actually flop a flush. Meanwhile, some players will c-bet on flush boards an even higher percentage of the time. In addition, some players will sometimes check back small flushes (anything smaller than ace high or king high) on the flop rather than bet. Consequently, a player who’s c-betting a flush-board flop may be even less likely to have a flush, and thus even more likely to have air.
In other words, if a player c-bets on flush boards 60 percent of the time, depending on the player, that 60 percent c-bet range might consist of 40 percent air and 20 percent flush — or 45 percent air and 15 percent flush, or 50 percent air and 10 percent flush, and so on — even though he might flop a flush around 30 percent of the time.
This means that if you are the big blind in this situation, you should be check-raising the flop with some regularity against most players, and especially against players who c-bet on flush boards up in the 60 percent to 70 percent-plus range, because at that point, the discrepancy between how often the player is betting and how often he is both betting and holding a hand that can stand a check-raise (that is, a flush) is simply too great not to take advantage of (we’ll talk about adjusting to check-raisers in a future column).
This brings me to the flush-board c-bet percentage statistic.
PokerTracker: Flush-Board C-Bet Percentage
The problem with the flush-board c-bet percentage statistic is this: It is not built into any of the poker tracking software. To solve this problem, I asked the support staff at PokerTracker to create a custom statistic.
The nice thing about PokerTracker is that it is a living piece of software in which you can create a new statistic yourself, or otherwise request to have one made. While the flush-board c-bet percentage statistic is not built into the software, you can go to the pokertracker.com website and download it by clicking “Get More,” and then “Statistics” in the side navigation. The statistic is labeled Cbet Flop — Flush Board (Omaha). ♠

Jeff Hwang is a semiprofessional player and author of Pot-Limit Omaha Poker: The Big Play Strategy and Advanced Pot-Limit Omaha: Small Ball and Short-Handed Play. He is also a longtime contributor to the Motley Fool. His latest two books — Advanced Pot-Limit Omaha Volume II: LAG Play, and Volume III: The Short-Handed Workbook — were released in October 2010. You can check out his website at jeffhwang.com.