The term “gap concept” was first introduced by professional writer and poker player David Sklansky in his book “Tournament Poker for Advanced Players”. Every good poker player knows about this theory: If you are thinking of entering a pot that has already been opened, you need a stronger hand to call than you would need to open the pot yourself. In this article I am going to explain why the gap concept is a very important factor which applies to both tournaments and cash games.
Think about this scenario. It is early in a poker tournament; you sit in middle position with Ace Ten, which is a decent holding. The action folds to you. What do you do? You should probably put in a raise in this situation because you have a decent holding and position.
But what if you have the same hand, in the same position, but a player in early position enters the pot with a raise? What hand range can you expect from an UTG raiser? More than likely, Ace King, Ace Queen, or a high pocket pair. Considering how likely the hand is dominated, your Ace Ten quickly turns into a hand that belongs in the muck.
The actual “gap” is the difference between a hand that is worth calling a raise with, and a hand that is worth entering a pot first in with. The basic starting hand strategy says that the earlier you have to act in a hand the better hand you need to enter the pot. Most players know this. If you sit in middle position and someone raises from early position you can put the raiser on a premium hand. Therefore, it is possible to get rid of a hand like Ace Ten and Ace Jack in that situation.
The gap concept is also important to have in mind when you put in a raise from early position and someone decides to call or raise you. Let’s say you have Ace Queen in early position and decide to raise three times the big blind. A player in middle position then puts in a pot sized raise. What should you do? I won’t say that you always should fold in this situation, but if your opponent has knowledge about positional play and the gap concept, folding should definitely be an option. He knows that it takes a premium hand to raise from early position, and his re-raise indicates that he think he can beat your hand. Your opponent’s likely holdings are therefore QQ, KK, AA or AK, and you are an underdog against all of those hands. If he would have a smaller pair it would be a coin-flip, and he probably wouldn’t raise you with a smaller ace.
Other considerations are player types and chip stacks. It is a huge difference between a raise from a very loose player and a raise from a “rock”. The loose player may raise with any two cards over ten, while the rock only raises with a premium holding. If a short stack moves all-in it doesn’t have to mean he has a good hand, he might just gamble and try to double up. He could have almost any two cards. The same goes for the huge stack. He doesn’t fear elimination and can afford to gamble with a questionable holding.
If you combine, good starting hand requirements, knowledge about position and player types with the gap concept you will be on your way to become a winning poker player.