progressBB defense vs CO open at 55 BB
8-max MTT · ante 12.5 % · Cutoff opens, small blind folds · chip EV
How the BB defends at 55 BB
Facing a Cutoff open to 2.1 BB (small blind folds) with 55 big blinds, the big blind folds only 22% of hands, calls 64%, 3-bets to 9.5 BB with 13% and goes all-in with 0.1%. 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, AQo, AJs, AJo, KK, QQ, JJ, TT, 99, 88, 77.
Folded: Q6o, Q5o, Q4o, Q3o, Q2o, J3o, J2o, T5o, T4o, T3o, T2o, 95o and 9 more.
Against other openers at 55 BB the big blind continues with: vs BTN 87%, vs HJ 78%, vs LJ 74%, vs UTG+1 71%, vs UTG 70%. 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): 63o 52%, K3o 58%, 52o 40%, J4o 38%, J5o 64%, K2o 32%, plus 2 more mixed hands. These are the hands worth drilling, because a small change in the opponents or the stack flips them.
What changes around 55 BB
The book continues with 78% of hands here, 78% at 50 BB and 77% at 60 BB. Going from 50 BB to 55 BB, no hand crosses the 50% line; only the frequencies shift.
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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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