Underbluff sizing is important

A lot of players at the mid stakes and lower levels of no limit do not spend time thinking about their bluff bet sizing....

Posted Apr 16, 2014


Bart Hanson BW2

Bart Hanson

Owner and Lead Pro

A lot of players at the mid stakes and lower levels of no limit do not spend time thinking about their bluff bet sizing. I have seen many players make ridiculously large bluffs when their opponent will basically not have anything or will almost always call. I often talk about players value betting rivers with only a polarized range—that is very strong or very weak. But there are also situations where players will have a polarized hand strength given the action.

If a player is strong and will call down your bluff almost always or he is weak and will never call your bluff what do you think the best play is in terms of bet sizing? If you guessed small, you are correct and thus you can see the power of under bluffing. Now this concept can be a little bit confusing because people are not going to always have polarized hand strength on the river. You very well might be able to bluff someone off of an overpair if you raise flop, bomb turn and bomb river but what I want to discuss in this article are situations where your opponent has a big hand like two pair plus and will not fold or has a missed draw.

I played a hand at the Commerce Casino last week that was a great example of this concept. The game was $5-$10 and effective stacks were $1000. I was in the cutoff and flat called the highjack’s raise of $40 with 4 5. Both the blinds called and the UTG limper, who was the villain in the hand, also called. The flop came out Q 3 6 giving me an open-ended straight flush draw. It got checked over to the preflop raiser who made a rather weak bet of $50. For my hand, this spot was about as good as it can get in terms of fold equity and I decided to raise to $215. Both the blinds folded and shockingly the UTG cold called. The preflop raiser got out of the way and we saw the 8 turn. The UTG and I had about $1000 left in the hand. I had played with this guy for many years and he wasn’t the type to limp in with AQ or KQ under the gun. If he did limp in with a random queen he also was not going to cold call a bet and a raise on that flop. I squarely put him on either slow playing a set, Q X or the nut flush draw. In reality I thought it was unlikely that I was going to get him off of any of those hands on the turn, with the exception of maybe the nut flush draw, so decided to check behind. Now some people might say that I was giving up on the pot but I did not want to basically be forced to call an all-in check raise with such a huge draw. Now comes the interesting part. The river was the Q, he took some time and checked again. If I was playing at a higher level, I might very well think that a player could be checking an under boat to induce a bluff (and also not worry about missing value because a queen will bet the river anyway) or a queen here at the end. But most guys at $5-$10 really are not at that level and are doing many things—bet sizing, bluff frequency, call down frequency—based upon their own hand strength not playing off of their opponent’s range. However, the villain in this hand did have a history of being a little cagey and even though he is only a recreational player is definitely well experienced. I thought that there was maybe a 30% chance that he was checking to induce a bluff and a 70% chance that he had missed the nut flush draw. If I did not think that he would ever call with ace high here at the end--and that thought is reasonable because I do have queens that I may raise flop with versus the weak preflop raiser’s continuation bet--what should my sizing be? The pot is $630. I decided to bet $150 to get a really good price on my bluff. I wanted to make it enough where there was absolutely no chance that he would call with ace high and if he is trapping me with a queen or a boat no amount is going to make him fold anyway. He released his hand rather quickly and the dealer accidentally exposed his cards as A T. Could I have possibly gotten him off of his hand on the turn if I had continued to fire? Yes, but you can see that I actually risked less money by playing the hand in this manner, using my position and overall awareness of poker theory. Remember the nut flush draw is only a portion of his range. He could have easily had some of those bigger hands that I mentioned earlier.

This is one of the most under thought situations in no limit games. Players never evaluate the sizing of their bluffs. The queen coming on the river here makes this situation really easy especially when someone is not advanced enough to recognize the situation and check a big hand. A more interesting spot would arise if say the river was entirely a blank and you were up against someone that would cold call your flop raise with just top pair. Now a larger sizing, if you think it actually would add more fold equity, could be prudent. In this situation your opponent’s hand strength is not polarized at the end. I definitely would hesitate to recommend bluffing blank rivers, however, if you checked back the turn. One of my favorite things to do, and I have mentioned it many times in these articles, is to raise on the flop with 45 without clubs, check back the turn and then rep the front door flush when it comes in. That makes a single paired hand awfully difficult to call.

You can also underbluff the river when you are the preflop raiser and the board runs out in such a way that it is difficult for medium strength hands that may have check called on the flop to call down three streets. This happens a lot when there is a possibility that your opponent may have picked up a backdoor flush draw on the turn to go along with his pair or straight draw. That is why it is important to notice the distribution of the suits on the flop even on rainbow boards. Let us take a look at another example. Say we raise to $20 from the hijack in a $2-$5 game with K J playing $700 effective. Only the big blind calls us. The board runs out 9 4 2. The big blind checks and we decide to fire out $30 knowing that it will be difficult for him to call multiple barrels if over cards come. He makes the call. The turn is the Q bringing in a backdoor flush draw. He checks again, and we put out a second barrel of $80 representing the overcard and also picking up a gutshot straight draw. Our opponent thinks for a while and calls again. What type of range do you think that he could have here? Let us assume that he now folds all pairs 8 or below that have not picked up a draw. So A4, 45 that are not hearts are out as well as deuces that are not hearts. He could sometimes still be stubborn with a 9 but due to the flop suit distribution you can see that he cannot have 9 X. He also may have straight draws that have picked up hearts on the turn like 5 3, 5 6, A 3, and A 5. The river is the A. The pot is $260. What should be our sizing? Let us assume for a moment that we are never going to get him to fold A3 or A5 or any two pair. However, a small size will make it almost impossible for him to call with a 9 or a 4 or deuce that picked up hearts on the turn. I contend that you can get away with betting as little as $50-$75 here to pick up the pot. That would be a classic three-barrel underbluff line worked to perfection.

If you were to take one thing away from this article remember there always should be a reason why you are bluffing a certain amount and it has way more to do with your opponents’ range rather than your own—just like most other aspects of big bet poker.

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