progressBB defense vs CO open at 38 BB
8-max MTT · ante 12.5 % · Cutoff opens, small blind folds · chip EV
How the BB defends at 38 BB
Facing a Cutoff open to 2.1 BB (small blind folds) with 38 big blinds, the big blind folds only 20% of hands, calls 65%, 3-bets to 9 BB with 13% and goes all-in with 1.0%. The big blind already has one blind in the pot and closes the action, so it gets a good price.
Always 3-bet: AA, AKs, AKo, AQs, AJs, AJo, ATs, KK, KQs, QQ, JJ, TT, 99, 88 and 1 more.
Folded: Q5o, Q4o, Q3o, Q2o, J2o, T5o, T4o, T3o, T2o, 94o, 93o, 92o and 6 more.
Against other openers at 38 BB the big blind continues with: vs BTN 88%, vs HJ 78%, vs LJ 75%, vs UTG+1 72%, vs UTG 71%. The later the opener, the wider its range, and the more the big blind defends.
Closest decisions (the book continues with them only part of the time): J4o 50%, 52o 54%, K2o 32%, 95o 30%, K3o 72%. These are the hands worth drilling, because a small change in the opponents or the stack flips them.
What changes around 38 BB
The book continues with 80% of hands here, 80% at 36 BB and 80% at 40 BB. Going from 36 BB to 38 BB, no hand crosses the 50% line; only the frequencies shift. With the extra chips some former all-ins become small raises: AQo.
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Numbers come from the progressGTO solution book (v14, chip EV, 8-max, ante 12.5 %): our own equilibrium computation with a modelled postflop. It is an approximation, not an exact solution, and it keeps improving. Hover or tap a hand to see its exact frequencies.
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