Pot-Limit Omaha: The Flush-Board Check-Raise Percentag

In my last column, I discussed the flush-board c-bet [continuation-bet] percentage, a custom-made statistic that PokerTracker 3 users can download from the PokerTracker.com site. I noted that when the flop comes all of one suit in Omaha — making a flush possible — the probability that your opponent actually has a flush is roughly 30 percent in a heads-up pot. However, in pot-limit Omaha (PLO), your opponents — particularly the tougher, more aggressive ones — are generally c-betting far more often than that, especially on flush-board flops.
Let’s say that it’s a $1-$2 game online with $200 stacks. The button opens with a raise to $7, and only you call from the big blind. The flop comes J♥ 6♥ 2♥; you don’t have a flush, and you check to your opponent. He bets $7.50, or half the pot.
While the typical player c-bets roughly 50 percent to 70 percent of the time in PLO, many players follow through with a c-bet even more often on flush-board flops — some well north of 80 percent. And the reason that they do this is because the average player these days too often will simply fold to a c-bet unless he has a flush himself, making flush-board flops easy c-bets.
However, as a consequence, flush-board flops are also easy check-raise flops. If a player c-bets 60 percent of the time but actually flops a flush only 30 percent of the time, his bet should probably be met with a check-raise with some frequency. For one thing, if your opponent bets $7.50 and you check-raise to $22.50 — three times his bet — you have to win the pot outright only 50 percent of the time to break even. And when you consider that many players check back small flushes from time to time on the flop, a player who is c-betting flush boards 60 percent of the time will have a flush less than half the time.
That said, opponents with flush-board c-bet percentages significantly more than 60 percent should probably be check-raised just on principle.
But what if the positions are reversed, and you are the c-bettor facing a check-raise on a flush-board flop? This brings us to the flush-board check-raise percentage.
The Flush-Board Check-Raise Percentage
To address the reverse position, I asked the PokerTracker support staff to create the flush-board check-raise percentage statistic. This stat, too, can be downloaded from the PokerTracker.com site.
The flush-board check-raise percentage measures how often an opponent check-raises on flush-board flops. The next question is, how often is too often?
The answer is that it is hard to say. For the most part, the typical player does not (and should not) check-raise with non-nut flushes, which are decidedly small-pot hands. Consequently, a check-raiser’s range should consist of three basic types of hands:
1. The nut flush
2. The bare ace of the flush suit
3. Air
This means that a check-raiser on a flush-board flop generally will have a flush far less than 30 percent of the time. In fact, based on my own flush-board check-raise percentage, I would guess that a check-raiser will have the nut flush somewhere in the low single-digit range, as in 3 percent to 5 percent.
As such, I think anybody with a flush-board check-raise percentage in the high single digits or greater is a good candidate for a three-bet bluff.
Three-Bet Bluff on the Flop
The game: $1-$2 six-max PLO online, six-handed
My position: Cutoff
My hand: A♣ Q♥ 5♣ 3♥
Seat 1: Hijack ($821.05)
Seat 2: Cutoff/Me ($325.10)
Seat 3: Button ($186)
Seat 4: Small Blind ($202.75)
Seat 5: Big Blind ($354.10)
Seat 6: Under the Gun ($200)
Preflop: I ($325.10) open with a raise to $7, and only the small blind ($202.75) calls.
Flop ($16): 10♦ 5♦ 4♦. My opponent checks. I bet $9. My opponent check-raises to $43. I reraise to $99, and my opponent folds.
Other Factors to Consider
There are several factors to consider. For one thing, the major drawback to these flush-board statistics is that they require an exceptionally large number of hands in order to generate meaningful data, because these situations simply don’t come up that often; not only does a player have to be involved in a hand in which three of a suit hit the flop, he also has to be either the preflop aggressor in order to generate a c-bet statistic or a player who’s out of position in order to generate a check-raise statistic. As a result, it might take 10,000 hands with a given opponent to generate just 50 opportunities for him to both c-bet and check-raise on a flush-board flop.
This leads to a sample-size problem. A player who check-raises three times out of 50 has a check-raise percentage of 6 percent, while a player who does so five times has a check-raise percentage of 10 percent. Meanwhile, it just could be that the latter player simply flopped the nuts a couple more times in 50 flush-board flops.
In addition, I’d guess that most players who are playing lower than 50¢-$1 online probably don’t check-raise enough on flush-board flops for you to worry about three-bet bluffing them. As such, the flush-board check-raise percentage will be a much more useful statistic for small- and medium-stakes regulars than it will be for casual players or micro-stakes players. ♠

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.