Pre-flop Controversy

[beetman]

I am kind of confused as to what the postflop action was in this hand, but it sounds like the hero semi-bluffed the turn in a heads up pot with a flush draw and an inside straight draw, so we'll assume 12 outs. It also sounds like there was an ace on the board, not sure if it was in the flush suit, but for simplicity's sake I'll assume it is, and we'll ignore the fact that a couple of the flush outs will pair the board (not a huge deal for a heads up calculation.)

In that case, the hero has about a 27% chance of winning the pot on the turn, so betting and getting check-raised only costs 1.09 big bets versus checking behind on the turn if the hero has 0% chance of winning the pot with a semi-bluff on the turn. I don't know how big the pot is, but it has to be reasonably large since it was a family pot. Do you realize how rarely the semi-bluff has to work for it to have positive expectation? Keep in mind that the hero won't always be check-raised, either, and betting and getting called only costs .55 big bets versus checking behind if the hero has 0% chance of winning the pot with a semi-bluff. (These calculations also ignore how the play will affect the play of future hands, etc. etc.)

Anyway, as I don't know the exact play of the hand I can't say that semi-bluffing is definitely correct, but when the hero has a lot of outs, in this case 12, and the pot is fairly large, it is almost impossible for a semi-bluff to be
more than a small mistake.

To use a simple "worst case scenario" example, if the pot has 8 big bets in it, you'll only win the pot with a bluff 1 time in 20, will get check-raised 6 times in 20 and will get called the other 13 times in 20, betting instead of checking costs about 1/4th of a big bet if I did the calculations correctly, and that is pretty much a worst case scenario.
(Plus those calculations ignore the rare times when no-pair is the best hand and betting the turn lets you check it back on the river, for ex. when your opponent has no pair and a straight draw or a smaller flush draw.)