So 2 boards here. Q99 vs 322.

Think co rfi vs bb call.

I know theoretically we (as the co range) are supposed to use a smaller sizing on q99 and a larger sizing on 322 even though our equity is practically identical. It makes sense to me from an exploitative point of view but I'm trying to understand the actual theory behind all this. Does anyone here know the reasoning behind it?

Protection is more important on 322 for your weaker value hands, which win the most money when the opponent folds(if they're calling correctly, your flop bet will only reduce the opponent's profit, not wipe it out completely).

Think about the bottom of your value range on Q99 and how much action it can stand on different runouts.

Assuming BB flat calls to defend...

Almost always in poker, smaller bets get called or raised much more often than larger bets.

322 is mostly not interacting with either player’s range.

Q99 connects well with portions of both players ranges.

On 322 there is usually just no more poker to be played. On Q99 there is lots more potential for either player to have a made hand or a draw.

Starting with a large bet on a connective flop texture is sub-optimal because it either ends the hand early, or blasts off into highly polar stack sized bets quickly. Betting smaller continues the hand more often, while not unduly narrowing the range of either player.

Starting with a small bet on a mostly unconnective flop is basically extending the flop to the turn, and squanders the CO range advantage on the flop. The hand should end on the flop, and betting larger gets it over with, or narrows down significantly the range of the caller.


This all depends on the c-betting strategy of the CO. If the CO is implementing a high C-bet frequency strategy, then the CO will likely use the same sizing on both boards. Probably around half-pot.

Also, the rank of the top card matters. A99 is way different than Q99. 822 is way different than 322. How about KQQ? Or QJJ? Some of these are bombs ready to ‘splode your stack, while others are hum drum.

thanks, very good/well explained answer. About this portion of your reply I'd like to discuss it further if you can offer more insight.

I know this is the general rule of thumb but I ran this spot through pio and was surprised to see that even though the x back frequency is almost exactly the same on both boards pio heavily favors the 23% cbet sizing on the q99 board (something like 60% iirc) whereas on the 322 board it only chose it like 14% of the time. The options were 23%, 53%, and 75% sizings. Also both boards were 2-tone.

So any idea why the 'more x back, bigger sizing' rule doesn't seem to apply here?

Slowly add combos of hands with a 2 in it to the BB call range. Slowly add A2s then start adding K2s, then Q2s, slowly a small percent at a time, and watch the solution change. It is pretty easy to have pio choose a large sizing to checking range.
With small changes in the starting parameters you can justify just about anything you want.

PIO is a tool, and it depends heavily on your input. What you input is based on your beliefs about the players, such as ranges and bet sizing options.

Also, I do not have a rule that correlates bet sizing to *assumed* checkback frequency.

‘Smaller’ vs ‘larger’ bet sizings can vary across different players strategies. For instance, I did not make a cbet of 23 percent pot size in 2018, and don’t plan to in 2019.

So, for me to even guess about why PIO says what it says when you enter what you enter is pointless.

Low paired boards are extremely sensitive to preflop range assumptions and it has to do with the density of trips in the defenders range.

You are allowed to put more money in on 322 because you benefit more from protection and trips compose a much smaller percentage of the defenders range as compared to Q99.

On Q99 you will face a raise significantly more often and protection is less of an issue.