Systematically designing a preflop range
Posted by Leighton Acheson
Posted by
Leighton Acheson
posted in
Low Stakes
Systematically designing a preflop range
I am trying to build a preflop strategy based on data from Holdem manager and solver work. I decided to start with defending the big blind vs various open sizes from the small blind. I am using data from $10 zoom.
I observe that the small blind opens 41% when folded to (1700) instances. The most common open size is 3x, followed by 2.5x and min.So I ran a simple strategy over a (representative) sample of 33 flops for a 3x open. 
So here, any hand that has a number greater than 2 beneath it is more profitable to call than to fold. I'm pretty happy to now assume that these results are valid. What I don't know though and can't think of a way to figure out is "Other than premium holdings, what hands should I be 3betting?" If I 3bet and get 4bet, how should I proceed?
I don't have a big enough sample to figure out how people are actually responding to my 3bets in these spots and it would take years to build one. Also the solver runtime needed to start just toying with strategies is a lot. So I wonder if anyone knows how to figure out what approach to take with 3betting?
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For me this is a complicated question and I don't have a clear answer for you. What I would say though, is that if we want to design an exploitative preflop strategies, we not only have to take into account population preflop tendencies, but also postflop tendencies. For example if people have massive leaks in SRP as opposed to 3bet pots, we are more incentivized to call opens instead of 3bet and vice versa. So it's not clear to me based on preflop stats only what type of strategy I should be executing. Postflop skills is another factor.
Thanks for the reply.
Yeah, its definitely true that post flop tendencies will affect optimal exploitative pre flop play. However what I am really aiming for with the current study I am doing is to get a nice functional set of preflop ranges together to give me a platform to start analysing post flop play. When I am done studying preflop, I will start into looking for population tendencies post and I might well tweak these ranges based on what I find. One thing at a time though :)
I'm not saying that this won't help your game but absolutely nailing down which hand is the neutral EV one for you to call in a certain spot pre flop and calling everything better based upon your stats is not going to help you anywhere near as much as using the same energy to work on your postflop game because pre flop leaks are often very minor and if you're stronger than someone post flop will often turn into +EV plays anyway. I think pre flop is easy to get fixated on because everyone has this sense that they can perfect it and attempting to perfect even one aspect of post flop play is a daunting if not impossible task. Just think how often you've seen high stakes pros deviate from pre flop charts because they're fine making marginally losing plays here in order to win more post.
I understand the points you are making but I think you might underestimate just how much value one can get from doing this type of study. First off, having a more strongly defined sense of how wide your range is preflop helps you to make better decisions postflop. Also, having a simple but systematic approach allows you to stop second guessing whether you should defend K7o or not, freeing up mental bandwidth.
Most importantly though its not just the size of the mistakes you make in a given spot that impacts your winrate, its also the frequency that you are in that spot. Having spent all this week looking into various preflop spots I have increased my opening frequency in the small blind from 30% to 65% and on the button from 38% to 55%.
I intend to study preflop for maybe 40-60 hours more before moving on to systematically approach flop play, building on the ranges I am identifying.
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