When you bet $0.80 on the
flop and $2 on the
turn, this is how BB's
stack progresses through the hand:
On the
flop, BB has $8.45
behind.
On the
turn, BB has $7.65
behind.
On the
river, BB has $5.65
behind into a pot of $7.65.
If instead you bet $1 on the
flop, the
turn pot will be $4.25 and BB would have $7.45
behind. If you bet $2.45 on the
turn, the
river pot will be $9.15 and
Villain will only have $5
behind to
push, making the
river an easy
call against his
range.
Another quick consideration for bet-sizing against possible draws: suppose he had a
flush draw and the heart hit on the
river instead. On the
turn he would be calling $2.45 in a pot of $6.70 when he has $5.65 left
behind on the
river, so he would be getting almost exactly 5:1
implied odds assuming you always called his
shove when the
river hit the heart. At that point there are 44 cards we haven't seen yet and 9 of those help him,
giving him 4.9:1 on his money, making him slightly -EV on his
turn call even if you always
call the
river shove when the heart hits.
If you bet a little more on the
flop and keep the same percentage of the pot as a bet on the
turn, you can make his situation with a
flush draw even worse.