Our article for today introduces a convenient measure for connected flops- ‘straight number’. We address the strength of some common 3bet-calling ranges and investigate how to exploit different opponent types on the flop, turn and river. We make some observations on flops where our opponent’s range is particularly strong/weak and conclude with a reminder on critical points on such flops. To avoid repetition, assume that every flop in this article is nonotone. The presence of flush draws on connected boards completely changes our strategy and so two-tone boards are not included within the scope of this article.
Introduction to Straight number
We define the straight number of a flop as the number of different possible made straights on the board. In most instances, this is directly related to the total number of gaps on the flop: 0-gap boards (QJT-543) have a straight number of 3, 1-gap boards (KQT-542, KJT-532) have a straight number of 2, and all boards with 2-gaps of any form (JT7, J87, J97) have a straight number of 1. The exceptions to this general rule are, exhaustively, {432, KQJ, AKQ, AKJ, AQJ, A23, A24, A34} whose straight-numbers are {2, 2, 1…} respectively.
On most connected flops the straight number of the flop is the dominant factor in the theoretically correct line. Furthermore, it is so useful a measure that attempting to take exploitative lines whilst remaining ignorant of the implications of straight number leaves you at a significant disadvantage.
Simple comparisons
| Straight number | Example | Wide Range Straight Frequency | Tight Range Straight Frequency |
| 1 | T86 | 8.3% | 7.9% |
| 2 | T87 | 13.4% | 13.6% |
| 3 | T98 | 18.4% | 27.4% |
| 1 | A42 | 7.4% | 0.8% |
| 2 | 542 | 12.1% | 3.9% |
| 3 | 543 | 18.0% | 11.9% |
| 1 | AQJ | 8.1% | 14.5% |
| 2 | KQJ | 13.5% | 27.1% |
| 3 | QJT | 21.0% | 37.4% |
The ranges I have used above are at the extreme ends of the spectrum. The ‘wide’ range includes around 70% of hands and the ‘tight’ range the best 10% of playable hands (in my opinion). Neither range is a PPT top X% range as both are hand-constructed by me. The former range is useful when 3-betting HU and the latter when 3-betting a very tight opponent. The reader is encouraged to spend time himself modelling his opponent’s ranges on such boards for the more common 20-50% opening ranges.
Initial Impressions
The reader should notice immediately that their opponent tends to have a straight on a 1-straight board around 8% of the time. This means that failing to stack off with top or second set 100BB deep on a 1-straight board in a 3-bet pot is a theoretical leak. You can get away with folding exploitatively against the biggest of nits, but even against a polarized raising range with a very small bluff component you cannot fold sets on most 1-straight boards. You should notice also that wide ranges flop straights on 3-straight boards around 20% of the time. (On a tangent, I found the strategy on 3-straight flops so interesting that I am writing a subscriber post on it for August.) Against a competent opponent, C-betting with a very high frequency on these flops is lighting money on fire, especially if they like to play raise/fold on the flop.
Knowledge is Power
The 2-straight flops are where theoretical knowledge is most easily applicable. With your opponent flopping a straight only around 13% of the time, a player who tends to shove the nuts over a flop or turn C-bet severely weakens his river range. If (as most SS/MSPLO regulars do) he likes to call 2 streets with 2 pair or pair+Ocards+gutter but then fold unimproved on the river, 2-straight flops are excellent triple barrel candidates. If your opponent is willing to sandbag two streets with his straights then he leaves himself open to back-door flush draws, he will need to call flushing rivers with at least some of his straights to prevent you tripling the back-door every time it hits. If you keep a sharp eye on your opponent’s tendencies, 2-straight flops should be very profitable for you. Of course if your opponent is one of the regfish who plays shove/fold on these flops you won’t get to do any of this interesting poker-stuff, but you already know how to exploit them, right?
Nuances of Range
You will have noticed that the tight ranges completely obliterate mid-high heavily connected boards and that against such opponents it is wise to shut-down completely with most of your air. Of course, your strategy is affected by the strength of your range, but once your opponents start flopping sets-or-better 35+% of the time on these flops there isn’t much room to play at only 100BB deep. What is far more interesting is the difficulty tight opponents face on low flops. On A42 your tight opponent has 35xx a comically low 0.8% of the time. Coupled with him 4betting most of his AA and AA still being in our range and this is a board where we should C-bet 100% of our range. In fact, the disparity in respective range strength is so great that there is an argument for checking our nutted hands on occasion to generate action on the turn. Less obvious is the 542 board; here many tight players will fold QQxx on the flop (if they called it pre-flop) and so are folding to C-bets with a really high frequency. Their turn range is also quite transparent, in that it consists of {overpairs, 67, pair+gutter} and many players will prefer to shove 9875 or similar. The wheel flops in general make for very profitable 1/2-barrels against tighter opponents. A smart adjustment for them is to flat their 54xx, but you will find many who shove this on the flop, again exposing their turn range to aggression
A reminder on critical points
We take the T87 flop as an example, where our opponent has a straight only 13.5% of the time. If we bet half pot/60% pot/ 60% pot on turn/river bricks our opponent needs to felt 21% of his overall range. Since a wide range will only have a set 5.6% of the time on the flop (and pick up a few more by the river when he calls overpairs) our opponent has no choice but to call down all sets or better if he raises none of his range on the flop. Of course, once he raises the nut straight on the flop he removes the top 7.5% of his range, and (assuming a 2:1 nuts:air ratio in a polarized range) 22% of his overall range. Now only 11.5/50= 23% of his turn range is set-or-better. If he wants to fold two pair by the river then he will fold too much to either an A4c double or triple-barrel. If we locate the bottleneck in his range, he will be very easy to exploit. Note that most players are unwillingly to call down with two pair on these flops, I strongly recommend barreling off here as a default and finding out what you get called down with (if you get called down).
This concludes our first article on the concept of straight number, I intend to follow this up with another article on straight number in single-raised pots. I would also like to thank my long-term subscribers for their patience in awaiting my second subscriber post. The blog received a huge influx of subscribers over the last fortnight and so I left the first post up longer than initially planned. A new subscriber post will go up early in August 2012. I have had a number of inquiries about the products page; the password for that page is different from the subscriber password. If you wish to gain access to the products page, please get in touch. Thanks for reading,
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