Against an opponent using an intelligent mix of bluffs and value bets, defending is always a hard chore. If you read a bunch of modern books on poker, you’re likely to come across topics like pot odds, minimum defense frequency, considering the effect of blockers (or the lack of them) on the size of your calling range, and discussions about what kinds of hands are thus best used for calling in various spots.
With pot odds, you compare the ratio of the bet you are facing to the size of the pot to see how often you need to be ahead to call profitably; with minimum defense frequency, you discover how often you need to call to keep bluffs from being profitable; with blockers, you’re able to make a more informed decision about the ratio of bluffs to value in your opponent’s range. This all can then be especially useful when all you have is a bluff catcher, a hand that loses to pretty much all of your opponent’s value hands, but beats basically all of their bluffs.
But what happens when your opponent is not a powerful AI, a solver, or even a top pro? This is presumably the situation most of us find ourselves in at Replay, and against more ordinary players, it’s unreasonable to expect a perfectly balanced ratio of bluffs to value. How do you change calling frequencies in such an environment?
If you remove even a few bluffs from what had been an optimally balanced range, the new solver solution will be to basically completely eliminate calls with “bluff catcher” type hands (and even hands somewhat better than that). Conversely, if you add even a few extra bluffs, rather than calling at GTO frequencies with these hands, you’ll shift to calling with nearly all of your bluff catchers close to 100% of the time (a maximally exploitative adjustment). Another way of saying this, is that against someone that doesn’t bluff enough, you can basically stop making hard calls, while against someone that bluffs too much, you should be calling much, much more often.
But making large adjustments like this is easier for your opponent to notice, exposing you to counter adjustments, and so if you think you have a thinking opponent that is paying attention to your play, a more measured modification that is less likely to result in your opponent adjusting their bluffing frequencies can often allow you to maintain a smaller but more consistent advantage over your opponent over a longer time frame.