explain to me the mathematics of a blocking bet

ipokeder · #1 08-15-2007, 02:02 PM

the use of "fake blocking bets" is very common in mid-high stakes as bluff-inducing bets, but personally i never use any actual blocking bets in my game and to an extent i feel like i'm not really sure what they are or what purpose they should serve. and since i don't use any real blocking bets, i don't think it makes sense for me to incorporate fake blocking bets against competent opponents, so i'd like for someone to explain to me the mathematics in which a blocking bet (excluding metagame considerations that i can make fake blockers in the future and whatnot) is the most +EV play

assuming the villian is rational and good

say for example, i have 44 w/ 4d on a 3c 6d 7d 8d 2d board and i block-bet the river

or i have JJ in an RR'd pot, the board is Qs Tc 5s 4c Th and i block-bet the river

are these examples of blocking bets? is a blocking bet fundamentally different from a bet/folding hand (because i always consider that a value bet, even if i'm thinly vbing an underpair or something but definitely folding to a raise)

i've always had the intuitive feeling that if i think i'm ahead in a hand i should be check/calling or value betting to get calls from worse hands or if i feel i'm behind i should be check/folding or bluffing to make him fold his hand, but i don't understand where block-betting comes into this (assuming block-betting is not simply bet/folding)

thanks

ipokeder · #2 08-15-2007, 02:14 PM

some ideas that i've had that i'm not sure whether they're right or retarded -

perhaps the purpose of an effective blocking bet is to polarize the range of our opponent's betting range such that the expected value of making any certain decision is also polarized so that worse plays become worse and better plays become better since his range is not as wide as when he has the initiative in the hand, so our average decision becomes more +EV and the variance in the outcome (that is, whether or not we made the right decision) of certain hand is smaller

or perhaps it's very useful in changing the size of the pot without actually making any kind of substantial action because the pot size we currently have would be inconvenient or difficult to play with

yes or no?

xorbie · #3 08-15-2007, 02:25 PM

block bet as a term is retarded and useful only against the most retarded of droolers who for some reason you suspect are going to go all in when you'd rather only put less than that in the pot.

value bets are good though.

ipokeder · #4 08-15-2007, 02:30 PM

well i swear to god in one of his videos sbrugby bet 44 w/ 4d vs a competent player on a board like that on the river OOP and called it a blocking bet

and why would you call it a fake blocker if you never use a real blocket? is it more accurately described as a fake thin vb then?

tcorbin16 · #5 08-15-2007, 02:54 PM

I use the Allin button as a blocking bet

Irishman07 · #6 08-15-2007, 03:23 PM

I think there could be some use for a blocking bet if you utilize fake blocks as well, especially if you're deep. Say for instance you're pretty sure villain has overpair or busted draw, and bluffs optimally so you can't call if he bets. If you bet ~1/2 pot with hands like tpgk, and occasionally a set it really makes it hard for him to raise because he's gotta risk a lot more if you come back over the top. Not sure if this really makes sense, and it gets really complicated because it depends so much on opponent's bluffing frequency. In theory I think it should work but in practice its tough to really gauge because not many people do it. Here's an example of a block bet gone wrong:

Full Tilt Poker No-Limit Hold'em, $4 BB (6 handed) Hand History converter Courtesy of PokerZion.com

saw flop|saw showdown

CO ($108)
Button ($334)
Hero ($400)
BB ($156)
UTG ($770)
MP ($251.40)

Preflop: Hero is SB with Q[img]/images/graemlins/heart.gif[/img], K[img]/images/graemlins/heart.gif[/img].
1 fold, MP raises to $14, 2 folds, Hero calls $12, BB calls $10.

Flop: ($42) T[img]/images/graemlins/diamond.gif[/img], 3[img]/images/graemlins/club.gif[/img], 2[img]/images/graemlins/club.gif[/img] (3 players)
Hero checks, BB checks, MP checks.

Turn: ($42) 8[img]/images/graemlins/club.gif[/img] (3 players)
Hero bets $20, BB folds, MP calls $20.

River: ($82) 3[img]/images/graemlins/diamond.gif[/img] (2 players)
Hero bets $40, MP raises to $124, Hero raises to $366 (All-In), MP calls $93.40 (All-In).

Final Pot: $665.40

Results in white below: 
Hero has Qh Kh (one pair, threes).
MP has As Ks (one pair, threes).
Outcome: MP wins $516.80. Hero wins $148.60. 

On the turn I figured I'd take a cheap stab at the pot and when original raiser called I put him on either overs probably with the flush draw or a mid pp. He was the type that wasn't gonna slowplay a set on the flop or a flush draw + overs. So when I bet the turn I was hoping to take it down but also for information/setting up a river play. I figured my 1/2 pot would be +ev since he probably had marginal pair/overs roughly 50/50 of the time. If he folds his overcards most of the time I'll be good the 33% I need to break even. When he raised though I could put him on a busted draw with pretty good confidence so I shoved. Unfortunately he was apparently a thinking player and we weren't deep so I got owned. But if I ever take that line with a flush against him now I know I can bust him.

Short version: Block bets could probably work, but against good thinking players its gonna be real tough to figure out the optimal strategy.

LearnedfromTV · #7 08-15-2007, 03:50 PM

Labeling a bet a bet/fold vbet or a blockbet is semantics if the bet is the same size, so I'm assuming by a blockbet you mean an abnormally small bet.

$200 pot on the river.

Your options are check, bet $50 (blocking bet), bet $150 (regular value bet).

Your opponent has you beat 35% of the time. If you check, he'll bet $150 45% of the time, bluffing 10%, value betting 35%, never checking behind a better hand. If you bet $150, he'll call or raise with every hand that beats you and he'll call w/ 30% of his worse hands. But if you bet $50 he'll call with 70% of his worse hands.

So check-calling is -EV: $350*(.1/.45) - $150*(.35/.45) = -$38

And betting $150 is -EV: $150*.65*.3 - $150*.35 = -$24

But betting $50 is +EV: $50*.65*.7 - $50*.35 = $5.

So that's the math.

Problem is, this example assumes he never bluff raises. And generally, if he's bluffraising some, he's probably going to bluffraise the $50 more often than the $150, which mitigates the advantage you get from him calling wider.

I generally agree with xorbie (blockbets are usually not the best option except against some fish, or at least against someone who is really predictable in a certain situation), but it seems like a decent time to use such a bet is on a fourflush board with a medium flush, like the 9. Any flush and maybe some other stuff will curiosity call and you get a little value that you wouldn't get from a normal bet. Works as long as you aren't likely to get bluffraised, which, against a decent oppponent, may require occasional fake blockbets with the nuts. I suppose against the right opponent you can fake blockbet a non-nut flush, although that's probably not the kind of guy an actual block would be good against.

PantsOnFire · #8 08-15-2007, 07:25 PM

I think the value of a blocking bet is not so much as an isolated play but as a combination of your play.

If we look at the size of the blocking bet, it is small and is similar to two bets, the probe bet and the post oak bluff.

If you can lay out these bets at different times plus throw in small value bets, you can disguise your blocking bet.

This obviously only works against observant opponents. So on the flop or the turn, a 1/3 pot bet by you could be a probe bet, a small value bet with a big hand, or a blocking bet to see another card cheaply. And on the river, a 1/3 pot bet could be a small value bet, a blocking bet or a post oak bluff.

If you can manage to mix up your play enough so that opponents aren't sure what you are up to, you blocking bets will be more successful. But then again, so will your other small bets.

Now is where the fun begins. Players will try to come back at you if they suspect a probe or blocking bet. If you have established that you can value bet small, now a re-raise will really get them thinking. On the other hand, if they are picking off your blocking or probe bets, the wait and make a small value bet and trap them for their raise.

I don't play enough with really good players so I rarely use the blocking bet. It usually goes right over their head. The only thing that works with these guys is to consistently value bet and cbet 2/3 pot and then throw out a 1/3 pot bet and see what happens.

This is the most complex game in the world so if I even go half of this right, I'd be surprised.

john kane · #9 08-15-2007, 07:41 PM

I never block bet. I either decide I'm likely ahead, and so decide to value bet/weak bet to induce raise/check raise river, or that I'm likely behind, and plan to check fold.

Blocking bets are so dumb as if they guy raises you don't know whether he has a very strong hand or is trying to bluff you given you weedy river bet.

DLizzle · #10 08-15-2007, 09:49 PM

blocking bets suck in general. If you play against the same competent players all the time it might be useful to have in your game if you feel you can level your opponent. Otherwise its a useless bet that gets bluffed way to often, and gets called by better hands. The only things it is good for is when your opponent has a hand that is semi-strong but worse than your hand, and you think they will call the bet but check behind if you check to them. So basically the only use for a blocking bet with the type of hand that the term blocking bet applies to is for value. So its just a value bet.

Often they are also useful as a fake blocking bet when you believe your opponent has air or when you have a monster and think lead/calling will get more money in than check raising.