Drill PokerMost leaks have loud reputations: tilt, loose calls, chasing draws without odds. Over-folding is a quiet leak. It produces no spectacular lost pots; you just fold neatly, hand after hand, and from the outside it looks like discipline. The problem is that against an attentive opponent, a predictable fold is a licence to bluff you whenever convenient. The tool that measures this leak is called MDF — minimum defence frequency.
The idea in one paragraph
When your opponent bets, he risks his bet to win the pot. If you fold too often, any bluff of his — even with two blank cards — pays for itself before any actual poker happens. MDF answers the question: what share of my range am I obliged to defend (by calling or raising) so that bluffing "any two" stops being free?
The formula fits in one fraction: MDF = pot / (pot + bet). A half-pot bet — defend at least 67% of the time; a full-pot bet — 50%. The bigger the bet, the more you may fold: your opponent risks more for the same pot.
Three anchor points that cover you at the table:
| Bet size | MDF |
|---|---|
| 1/3 pot | 75% |
| 1/2 pot | 67% |
| Full pot | 50% |
What it looks like in a hand
You open the button, the big blind calls. The flop misses you completely, and your opponent bets a third of the pot. "Missed — fold" is how a large share of the field plays, and at that moment their range folds in half — while against a third-pot bet, the norm is to defend three quarters of it.
What exactly to defend, the range itself suggests: pairs and top cards defend themselves obviously; next come gutshots, backdoors and hands with blockers to his value. The weakest third goes into the muck — as it should. The mistake begins when the middle of the range follows it.
Notice that MDF says nothing about your specific hand. It speaks about frequency. That is its practical power: at the table you don't have to decide "is my king-high good enough" in a vacuum — you have to judge whether it belongs to the 75% of your range you are obliged to hold.
When MDF can — and should — be broken
MDF describes defence against an opponent who bluffs at a balanced frequency. Such players are a minority, so the equilibrium frequency is a starting point, not a verdict:
- Against someone who doesn't bluff (which is most low-stakes regulars on the turn and river), fold as much as you like — nobody is there to punish your tightness.
- Against an aggressor who bets at every check, MDF understates it: defend wider than the norm and add check-raises.
- In multiway pots MDF is shared among the defenders: three players facing a bet can each fold more often than one heads-up.
- Against a bet near the money in a tournament, ICM shifts the mathematical norm — folding is cheaper than the chips suggest.
Breaking the norm consciously is what exploitation is. Only the unconscious over-fold is dangerous: when you believe you're "playing tight" while in fact any float takes your pot.
Where to train it
Frequency can't be trained by reading — only through hands where every decision's cost becomes visible. In the cash trainer the bot plays every hand out with you to the end, and the review shows equity and the price of the call at the key points; the GTO trainer separately builds the skill of defending against c-bets and check-raises — with equilibrium frequencies instead of a yes/no verdict.