04 Nov 2024 Intermediate This material is for medium-skilled players blinds defense GTO moving up stakes position There are a lot of intermediate and even advanced poker players that are convinced that MDF is GTO, and the truth of the matter is, that's simply not the case. Today we're going to talk about MDF, why it's not GTO, where these two numbers can differ massively, and what you should do about it instead. Let's get into it! Understanding Minimum Defense Frequency (MDF) Many players are convinced that MDF (minimum defense frequency) is specifically a GTO concept. And while there are overlaps, and even sometimes exact similarities in output, MDF is NOT truly GTO. The formula for MDF is simply pot size divided by pot size plus bet size - it’s easy: What MDF is attempting to do is tell you how much of your range you need to continue with, either by calling or raising, in order to ensure your opponent cannot auto-profit from bluffing you excessively. And that's just simply because if you are constantly over-folding, it's extremely easy for any opponent who's paying even the slightest bit of attention to start over-bluffing you, and just simply turning any two cards into a profitable bluff, because, well, you're folding too much, and they can make some very easy auto-profit against you. Now, although MDF is loosely based around GTO, there are some key issues that we really have to be aware of: An MDF calculation may differ significantly from the correct GTO defending frequency; The frequency itself doesn't actually tell us which type of hands to defend with nor how. Since defending simply means that we're not folding, but we could be raising, we could be calling, we could be doing a combination of both of those things, so just having a raw number to work with doesn't exactly tell us how to continue best. Comparing MDF and GTO When OOP So with that said, let's take a closer look at developing some defense strategies - both in position and out of position. So let's start with out of position first. We're going to take a very basic situation and compare what MDF numbers look like compared to GTO defense frequencies in a very basic situation: Button opens, preflop, big blind defends, big blind checks to the button on the flop, and let's look at a couple of different cbet sizes that the button could use and the appropriate MDF and GTO defense frequency that come out of the solver. So this table looks at four different possible cbet sizes that the button could use, ranging from 33% pot all the way up to 125% pot, and what we notice is that the MDF number is consistently larger than the GTO defense frequency, right, even against the half pot bet, the MDF is 67% two-thirds, but the GTO defense frequency is 57%. Even against the overbet, MDF is going to be 44%, but the GTO defense frequency is down lower, again, at 37%. So what we learn from analyzing data like this, and by the way, this kind of pattern comes up a lot, is that GTO defending frequencies are consistently lower than MDF calculated values. If we were to strictly use MDF to derive our flop defense in this scenario, we would be defending significantly too wide and carrying way too many hands into the turn. Now that all being said, formation is definitely going to play a role here, and there are a couple things that we can take away from that: We do fold slightly more in general when the original opener was in earlier position, and obviously in this situation, the opener was on the button; We fold slightly less when we are the small blind cold caller as opposed to the big blind cold caller, mostly because those two calling ranges tend to be significantly different. So for instance, if we modified this scenario where we were looking at the small blind as opposed to the big blind for the preflop defender, we would actually notice that the small blind is only folding a few percentage points above MDF, but if we actually change the spot altogether for big blind versus under the gun, now all of a sudden it's 15% above MDF. MDF calculations aren't super far off in every single situation. Analyzing MDF and GTO IP For instance, if we switch it, instead of looking at out of position, we look at in position instead, what we actually notice is that defending frequencies correlate very closely to their respective MDF values when we're looking at in position as opposed to out of position. If we analyze the same chart we looked at earlier but flip it for an in position defense as opposed to an out of position defense against a cbet, what we actually notice is that these numbers are very similar. Against a 33% sizing, MDF and GTO defense frequencies, the exact same. Even at the overbet, 44% for MDF, 43% for GTO defense frequency, those are extremely similar and we notice this for all sizes within the spectrum. And just like out of position, even in position there are still going to be formational differences, but defending at a round MDF value is fairly consistent when playing in position as the defender. And as an important side note while we've been looking at single raised pots so far, you actually notice this exact same pattern come up in 3bet pots as well. The in position defender in a 3bet pot is going to defend close to MDF while an out of position defender will be overfolding according to MDF to a degree that depends on the precise formation and also board texture. Alright so at this point you should have the big picture idea understood that pure MDF calculations are not the exact same as pure GTO and also that being out of position is going to influence the differences between those two numbers more significantly than being in position overall. MDF Thought Experiment I think it would be helpful to go through an MDF thought experiment if you've never really gone through this and thought through this like this before. Now keep in mind that this is off the heels of noticing the out of position discrepancy, right, the situation where facing a half pot bet the MDF is 67% but the GTO defense frequency was just 57%. So many players struggle with the idea that the in-position aggressor is now generating automatic profit when they continuation bet against us. They think to themselves the point of GTO defense is to prevent our opponent from generating automatic profit, correct? And from the perspective of the entire game tree the answer is of course yes, however from the perspective of an individual hand the answer is a clear no. Consider the following thought experiment which exposes the weakness of MDF calculations. Imagine a spot where our opponent's range on the river is exclusively full houses, our range is exclusively mid pairs, and our opponent bets pot on the river. First, what is our MDF and second, what is our GTO correct defending frequency? According to MDF we need to defend our mid pair 50% of the time despite the fact that we will always lose when defending, right, because MDF tries to make sure that your opponent cannot generate an auto profit so it continues 50% of the time based upon their bet size but of course we always lose when we do end up calling. Contrast that to the GTO correct defending frequency which is 0%. GTO would never call if the EV is negative even if the end result is automatic profit for villain. What we learn is that it is acceptable to give our opponent automatic profit. When the roles are reversed, our own strategy will generate an equivalent amount of automatic profit against villain. The net result in a perfect GTO game is zero profit across the entire game tree. Automatic profit in individual hands is a common feature of GTO play. However, which is why the concept of MDF becomes unreliable. So I think with that thought experiment out of the way and all the other stuff we talked about in this article, this is a good place to put a pin in it. Key Takeaways on MDF and GTO Again, one of the biggest possible takeaways you can get from this is that raw MDF is not the same as pure GTO. So if you're just trying to think, oh I'm a GTO player because I'm using MDF, that's not really the way you want to think about it. You might be closer than someone who has no defense frequency strategy, but you're not going to be pure GTO by any stretch of the imagination. Thank you so much for hanging out. If you have any comments or questions, please don't hesitate to let us know. And if you learned anything at all, a comment on the article would be massively appreciated. We'll see you back shortly with a couple of brand new articles. And in the meantime, good luck out there and happy grinding!
