When should you c-bet again on the turn?

2024-09-10

I found a hand recently which I think is interesting to analyze. This hand involved two mistakes in situations that are both in the top 25 situations where mistakes occur in the heads up game tree for humans versus bots. In the 100,000 hand sample I'm looking at, the total EV loss from these areas averages 7.3 BB per 100 hands. Read more about how I split the game tree into situations in this post.

Let's dive right into the action.

You, as the human player and therefore the hero, raise preflop with QTo from the BN and get called by the BB, who is the GTO bot and therefore the villain. So far, this looks standard. QTo is squarely in the BN's raising range. If the BB had re-raised, the BN would mix between folding (40%), calling (48%), and raising (12%). Let's see a flop.

On the flop, the BB checks, as he should with 94% of his range. As the preflop aggressor, the BN gets to bet the majority of his range on essentially any flop, and this flop is no exception. On this Kh9h2s flop, you should bet small with 59.6% of your range, as the chart below shows. With your particular holding of QTo, you should be betting small 55% of the time, checking 34% of the time, and betting large with the rest of your range. You decide to go with the mainline option by betting 2 into a pot of 8.

At this point, you haven't really narrowed your range at all, since most of your range bets the majority of the time simply because of your range and position advantage given the preflop action and your position as the BN. On the other hand, when the BB calls, his range narrows and strengthens. The following chart shows the BB's range distribution for the decision of whether to fold (yellow), call (blue), or raise (red) in response to your small c-bet. Notice how much of the BB's high card range disappears if he decides to fold. His decision to call strengthens his range here. Whereas the bottom part of your range mostly fired off a c-bet, the bottom part of his range mostly folded. This is something you should consider as you approach the turn.

On that note, let's see a turn.

The turn is where you make your first mistake. The BB's strategy should be to check again with at least 88% of his range on almost every single turn card. If you remember how the BB's range narrowed when he called your c-bet on the flop, you can probably guess what the exceptions are. Because the BB's calling range featured so many pairs, the scare cards are Kings, Nines, and Twos. In particular, Nines are the most scary, and the BB should bet 1/3 pot with 39% of his range on this particular 9. Nonetheless, he should still mostly check, which is what he chooses to do in this case.

With the action back on you, facing the turn check, you should be thinking about whether to c-bet again. The Nine is troubling, and you should realize the BB checked with some of his pairs which turned into trips. Nonetheless, you still get to c-bet about 40% of the time, and check with the remaining majority of your range. The question is, what should you do with this particular holding (QTo). The following chart shows what your strategy should be with your range of QTo. You should check almost all of the time, but when you do decide to bet, it should be a big bet. You essentially get to mix in some big bets with the trips you get to mostly raise big with. Nonetheless, the real mistake wasn't deciding to bet small instead of big; the mistake was not realizing that you should check almost all of the time. Save your betting for turn cards that aren't as favorable for the BB's range, such as turn cards which complete or improve your flush and straight draws.

Let's proceed to the river.

Going into the river, the BB's range consisted primarily of Ax, Kx, and 9x holdings, mixed in with some straight draws, as the chart below shows. The Kx and 9x holdings shouldn't be a surprise, but why did the Ax holdings hold on so long? Mainly because they still had reasonable equity against the weaker pairs, busted draws, and semi-bluffs you got to c-bet with the vast majority of the time on the flop, and a lot of the time on the turn. Because of this, Aces and Kings are actually the best river cards for the BB to wake up and start betting on the river (some of the time). The Two actually doesn't improve the BB's range much, and so he should mostly check for a third time, which he does.

Now that the action is back on you, it's time to decide whether or not to bet. The following chart shows your range breakdown. All of your full houses bet big. Your Kx holdings mix between betting small and betting big, and you mix in some bluffs. You generally should have checked back QTo on the turn most of the time, and so you shouldn't have it in this situation, but since you do, you get to bluff with it some of the time, and you do.

When the BB decides to raise, this is where you make the big mistake of calling, which costs you 11.6 in EV. Perhaps you were thinking that you were both playing the board, but the BB is rarely playing the board with his raising range. As the chart below shows, when the BB raises, he has a full house about two thirds of the time. Even your Kx range which makes a better two pair than the board can only call some of the time (using a mixed strategy). Even two pair with an Ace kicker is not good enough to call against mostly full houses.

Let's see the showdown!

As it turned out, the BB was at the bottom of his raising range with an A6o. This is a hand he should mostly check or call, while raising all in with a frequency of only about 4%. The GTO bots on ActionFlop randomize, so this was just one of those unlikely situations where the GTO bot essentially chose a random number between 1 and 100 and got something less than 4. Do you ever randomize like that when you're playing poker?

I hope you enjoyed this hand analysis. Stay tuned for more!