Reason 1 – Being in Good ShapeAt first, this reason might sound a little vague, but it can be elaborated upon in the following way:
Hero is in good shape and should call an open if his hand is likely to be ahead of Villain's opening range, but behind Villain's range for continuing to a 3-bet.
A good example of this reason in effect in 6-max cash would be holding a fairly powerful, but far from premium hand such as KJs, AQo, or 99 on the BU against a HJ open. Assuming that HJ is not a wild player, his opening range is perhaps somewhere between 18% and 24% of starting hands. If we 3-bet, the idea is that we filter this range into something we are no longer in good shape against, and although we do pickup some dead money when he folds to a 3-bet, we only gain this against the weaker parts of Villain's range, which we were happy to play against in position any way.
A good test for being in good shape is to ask yourself:
"If I call this open, and flop a common, but strong hand such as top pair or an overpair, am I content that my hand is very often best and able to extract a good amount of value?"
If the answer to this question is no, it is likely that Villain's range is too tight for us to play the decent, but non-premium hand in front of us, at least for the reason of being in good shape.
Let's imagine that in a 6-max cash game, UTG, who has been very tight and solid so far, open-raises to 3bb and we are in the CO with AJo. Our absolute hand strength here is reasonable, but our relative hand strength when we consider Villain's range is poor. When answering the above question, we are somewhat reluctant to say yes. When we flop top pair on Axx, we run into [AQ-AK] a lot more often than we would desire. When the flop is Jxx, there are 18 combinations of [QQ-AA] to worry about. This is not to mention all of the times when we simply miss the flop and lack the equity plus fold equity to continue against a c-bet. Villain's likely range here is so snug that we are rarely in good shape without a more premium holding. There is another reason to flat call some speculative hands in this very situation, but never ones like AJo.
Reason 2 – Implied OddsNot only was the AJo not in good shape in the example above; it had no redeeming features either. The main hopelessness of the hand resided in the fact that the one pair it regularly flops is too often dominated. Consequently, we would need to be hitting hands better than one pair on a semi-regular basis to grant any appeal to calling. AJo is simply the wrong type of hand for this mission. It flops better than one pair almost never, and when it does, it's still not fully safe from domination vs. a tight range of very big cards.
Hands that do a better job of out-flopping the top-pair-top-kickers and big overpairs of the world are classed as implied odds hands. This means that the money they lose from flatting an open, missing the flop, and subsequently losing the pot might be recouped and more by the semi-regular occasions where they flop huge and win a massive pot. This group of hands includes holdings like 44, which can make a very disguised and deadly set; 87s, which is more flexible, allowing for many ways to eventually best one pair; and A5s, which carries the latent threat of flush over flush. It is not that these hands are always callable against an open, but they certainly do not need to be ahead of an opening range to become lucrative calls. They make up for lost ground by winning a very large amount of money from time to time.
It is important that we see implied odds not as an opportunity, but as a ratio. More specifically, good implied odds will feature a low investment compared with a high average payout if we are lucky enough to make a nutted hand. Some beginners are very quick to call a gigantic 3-bet with 55, baited by the prospect of taking their opponent's stack when that elusive five appears on the flop. The problem here is that the 14bb 3-bet is just too large to set-mine against. The times we get there and win a large average amount of our opponent's stack are wiped out and then some by the times we miss and burn a very steep pre-flop investment. To call an implied odds hand, we need the ratio of average payout to pre-flop investment to be a favourable one. Here is a nifty rule.
To set-mine a pocket pair, we should think that we are capable of making 10x our investment back on average the times we flop a set.
This is because we flop a set roughly one in ten times. With a hand like a suited connector or suited wheel-ace, the ratio of risk to reward needs to be even better because these hands will improve to beat one pair more rarely than a small pocket pair will. Here are a few factors that will improve implied odds and boost the EV of calling an open for Reason 2.
Villain has a very tight range and so will often hold a strong hand with which to pay us off.
Villain is a bad player who is likely to bluff too much or call down too wide post-flop.
The effective stack size is deeper than normal (more money to be won)
We have position (this makes it easier to extract value post-flop).
Reason 3 – Pot Odds in the Big BlindBeing in the big blind increases our pot-odds greatly. When CO raises to 2.5bb, it costs us 1.5bb to call compared with the BU's 2.5bb to call. This is a discount that should certainly be taken advantage of on a regular basis, even with hands that do not qualify as a call for reason one or two above. The fact is that if we fold a hand in the big blind, our EV for that hand is -1BB per hand. Many of the hands we choose to flat a small open with in this seat will still lose us money, but they will lose us less money on average than if we folded. Perhaps their EV might be -0.86bb by flatting – a clear improvement.
For example, let's say that we call CO's small open with 98o. We are definitely not in good shape vs. his range, nor do we have a huge deal of implied odds, being out of position with a medium off-suit connector (though we do have some), the point is more that we have such a favourable price, that we simply do not have to perform very well post-flop in order to render calling more profitable than folding. In other words, we might not be able to jump very high, but fortunately, the bar is very low.
The other advantage to calling an open in the big blind is that we are closing the action. That is to say that no one can squeeze or flat behind us. Note that for these reasons, the small blind is nowhere near as profitable a place from which to defend against open-raises. Not to mention that our pot odds are worse from the small blind as our smaller initial investment leads to a smaller discount on the price to call the open.
Finally, if we have the luxury of being both in the big blind and in position against a smallish raise, then we should call a very wide range indeed. This spot occurs blind vs. blind. Against a 2.5bb open in this situation, some very speculative holdings get to join in the fun. Hands like Q5s and 86o become rare guests to a flop due to the major incentives of pot odds and position. Again, calling is perhaps not winning money in these spots, but it is losing less than folding. In other words, calling has a higher EV than folding.