# Method to determine ranges vs BU 3x open

• Diamond
Joined: 09.04.2010
Hi
I just faced a preflop spot and Im not sure how to deal with it.
The situation was:
Anon table
BU 3x, playing 14 13 over 15 hands so dont know what % he's actually opening.
Given some population reads i have on my site, I thought BU = 40%.

SB folds and i have A8o in the BB.
I folded.

It's been more than a year now I ask myself these types of questions and could not come up with a framework to "solve" the situation. So i thought some of the guys here could help me.

I'll give you some things to work on from then if you could tell me what's good, wrong in the way i try to solve the problem, that'd be great.

Math stuff
----------
Vilain needs 65% fe to profit.
SB et BB need to defend 35% combined.

Assumption #1: SB defends 7% passively and 3bet 8%.
fe of BU : 85%* x < 35%
>> BB/Hero must defend 40%.

- 12% 3bet
TT+, AJ+, ATs, KQo, some suited 3bet bluffs and blocker 3bet

This is usually what i 3bet when i dont have information.

- 28% call
This is the range i am usually confortable to defend with:
55-99, ATs-A2s, KQs-K7s, QJs-Q7s, JTs-J7s, T9s-T6s, 98s-97s, 87s, 76s,ATo-A8o, KJo-K9o, QJo-Q9o, JTo, T9o
= 22% only.

Assumption #2: Solution would be to 3bet 15%ish and defend 25% so that im not "forced" to defend k7o or hands im not comfortable with (wrong way of approaching the solution?).

A8o seems to be a call anyway.

-----------------
Scenario Analysis and EV:
I'll use CREV.

Preflop
BU range 40%
22+, A2s+, K2s+, Q5s+, J6s+, T5s+, 95s+, 85s+, 75s+, 64s+, 54s, A7o+, A5o-A2o, K9o+, Q9o+, J9o+, T9o

So I let all hands in BB's calling range that
a. mite be defends but
b. im not comfortable with and tend to fold in game

Flop
Assumption #3:
I just constructed a simple scenario where vilain cbets 70% flop
any top pair+
draws
backdoorflush draws
50% of air

Assumption #4:
hero continues on the flop with
any pair+
any draw
and let hero realize 70% of his equity (off?)

Assumption #5:
- if vilain checks back i assume i'll play a lil bit better and think he'll realize only 80% of his equity (too optimistic/pessimistic?)

- Decision tree:

- Results: +ev passive defends under previous assumptions:

The actual results dont matter for now - seems a bit off that A9o, K8s, 97s are -ev calls in such a spot in practice.

I just would like to know:
- what assumptions you would change and how
- what other factors you take into account
- do you further specify the model/scenario postflop
- ...

in order to get a better idea of what hands are or are not a defend vs such BU's preflop stats + flop frequencies.
• 5 replies
• Bronze
Joined: 28.01.2012
With SB+BB defending 35% this actually needs to be higher if you are defending by calling, 65% is assuming BTN has no equity share in the pot, and just gives up immediately every time with the worst bluffing hands in his range, whereas in reality there are flops which can turn his worst bluffs into monster hands, and he will also have a positional advantage as well which will increase the amount of pots he will pick up postflop.

Do you have any specific reasons for choosing the 3bet range you posted here? Seems kinda random to me, I can't think why you would be 3betting J5s and folding K5s
• Bronze
Joined: 07.07.2013
Against a 3x open a 40% defending range is very high. With head up I defend around 40% on the BB vs a 100% steal from the SB. Without postflop information from your opponent I would general play a little bit tighter. You don't know yet how he is reacting to check raising for example or If he check back all his non top pairs hands .
• Bronze
Joined: 19.06.2012
Villain risks 3 to win 1.5 so he needs 2/3 or 66.6% success and SB&BB need to 3bet 33.3% if they play 3bet-or-fold to deny profit from weak hands.

If SB&BB play a strategy of calling and 3betting, they need to defend more to deny profit from weak hands.

Exact models how much each blind defends how and which weak hand they should make break-even to open (32o or T5o or J7o) is almost unsolvable. There is some solid approximations in old threads and some coaching videos. And I have my own private ones .

For a start though, assume SB play 3bet-or-fold (this is likely very close to optimal against 3bb button raise) and 3bets around 17%.
• Diamond
Joined: 09.04.2010