A blocker is a card in your hand which reduces the chance your opponent from having one of the likely hands in their range. If you get to the river with AJ on a T42Q7 board, you do not have a made hand but it is impossible for your opponent to have the nut flush because you have the A. You can potentially bluff them on this board because you know they cannot have the nuts, because you have the blocker.
In recent years the importance of blockers has been greatly elevated. They impact all aspects of calling, value betting and bluffing.
We will cover blockers in detail in future articles but today let’s start with a simple but useful example of how valuable they are. It is the bubble of a satellite, you are the short stack Big Blind and the Button opens to two big blinds, you shove for 20 big blinds and in this spot you know your opponent can only call with the following range:
Would you prefer to have JJ or A5 suited in this spot?
How many combinations?
In a regular tournament where the calling range would be wider you would probably prefer JJ because it plays well against smaller pairs that could call you. In this spot, however, A5 suited is a much better resteal. Why?
The calling range of AK and QQ+ is made up of six combinations of QQ, six combinations of KK, six combinations of AA and 16 combinations of AK. That is 34 combinations of cards in total.
However, when you shove with A5 suited the fact you have the Ace in your hand reduces the number of combinations. It becomes six combinations of QQ, six combinations of KK, three combinations of AA and 12 combinations of AK. That is 27 combinations rather than 34, because the Ace in our hand reduces the overall number of combinations.
A shove with A5 suited should get called 20% less often than JJ on a satellite bubble. It also has some straight and flush equity when called.
It is a mistake to assume all bluffs are the same. Bluffing with 72o might make you feel like a hero but it rarely blocks something meaningful. Bluffing with an Ace in your hand is going to be more successful because you have an Ace blocker.
How blockers play a role in pots where you chase draws
Blockers in PLO
Twice as many cards, twice as many blockers