The Short Stacker

40bb and one question on every street: is this all-in strong?

The Short Stacker buys in short, for 40 big blinds, looking to double up. They get the stack in with good hands and strong draws, give up weak ones, and bluff in exactly one spot. With 40bb a good hand turns into an all-in fast, so most of your decisions come down to one question: is this all-in strong?

In short

Respect their all-in: a jam is the all-in pile and never a bluff.
Bet half pot or more to fold their weak hands: middle and bottom pairs call only 1/3 pot.
When they check as the raiser, bet: their strong hands would have bet.
Fold medium hands to their river bet: they don't bluff there.

Before the flop

The Short Stacker never limps. They open tight from early seats and wider later:

Seat	Raises first in
UTG	9% of hands
HJ	14%
CO	21%
BTN	32%
SB	21%

AAAKsAQsAJsATsA9sA8sA7sA6sA5sA4sA3sA2sAKoKKKQsKJsKTsK9sK8sK7sK6sK5sK4sK3sK2sAQoKQoQQQJsQTsQ9sQ8sQ7sQ6sQ5sQ4sQ3sQ2sAJoKJoQJoJJJTsJ9sJ8sJ7sJ6sJ5sJ4sJ3sJ2sAToKToQToJToTTT9sT8sT7sT6sT5sT4sT3sT2sA9oK9oQ9oJ9oT9o9998s97s96s95s94s93s92sA8oK8oQ8oJ8oT8o98o8887s86s85s84s83s82sA7oK7oQ7oJ7oT7o97o87o7776s75s74s73s72sA6oK6oQ6oJ6oT6o96o86o76o6665s64s63s62sA5oK5oQ5oJ5oT5o95o85o75o65o5554s53s52sA4oK4oQ4oJ4oT4o94o84o74o64o54o4443s42sA3oK3oQ3oJ3oT3o93o83o73o63o53o43o3332sA2oK2oQ2oJ2oT2o92o82o72o62o52o42o32o22

The Short Stacker's button open: 418 combos, about 32% of hands.

Their other habits before the flop:

Every 3-bet is all in. Between 3.5% and 6% of hands, widest from the button:

The Short Stacker's 3-bet from the button: 82 combos.

The cutoff drops the small suited aces (66 combos); the hijack and small blind are TT+ and AQ+ (62); the big blind TT+, AQs+ and AKo (50); under the gun TT+ and AK (46).

If you 3-bet them, they never call. They go all in with the grid below and fold everything else: 83% of their button opens, 44% of their under-the-gun opens.

What jams over your 3-bet: 70 combos.

If you go all in, they call with under 4% of hands:

The hands that call your all-in: 50 combos.

A call caps their range. They call with the middle, shown below: medium pairs, suited broadways and connectors, and a few offsuit aces and kings. TT+ would have gone all in.

The Short Stacker's call from the big blind: 172 combos, 13% of hands.

After the flop

Think of their hands in three piles.

The all-in pile: top pair with a good kicker (ten or better), overpairs, two pair or better, the nut flush draw, open-enders and combo draws (flop and turn), and any pair with a flush draw. These bet three-quarters to the full pot, by the board, and go all in when you bet into them or raise them, on any street. As the caller, first to act on the flop and turn, they check these hands to check-raise all in (only a pair with a flush draw bets instead). In a limped pot there is no raiser to check to, so they bet them.

Once less than three pots are left behind, weak top pair joins the pile. With 40 big blinds that is the turn after a half-pot or bigger flop bet and call (a 1/3-pot bet leaves just over three pots behind): top pair with any kicker then bets, and jams when bet into or raised.

The one-street pile: weak top pair (kicker nine or lower) and a bare flush draw.

Weak top pair bets the flop and calls up to 2/3 pot there. On the turn and river, while the stack is still deep next to the pot, it checks and calls only a small bet (your 1/3 button), and folds to a pot-size bet or a raise anywhere, and to a medium bet after the flop. Once less than three pots are left behind it's in the all-in pile instead.
A bare flush draw checks the flop and calls a small or medium bet. On the turn it calls only a small bet and folds to anything bigger.

The give-up pile: middle and bottom pairs check and call only a small bet, on any street, and fold to anything bigger. Everything else checks and folds to any bet.

Their one bluff: as the raiser, on the flop, they c-bet two overcards. That's it. On the turn those overcards check.

Say the Short Stacker raised from the button and you checked:

J♥8♥3♣

They bet 165 of 377 combos here.

Those 165 are 78 from the all-in pile, 29 strong draws, 12 weak top pairs (J9) and 46 of two overcards (AK, AQ, KQ). The 212 that check are middle and bottom pairs, bare flush draws and air.

Same hand: they bet the flop and you called, leaving 16.5 in the pot and 32 behind, under two pots.

J♥8♥3♣5♦

On this turn they bet 119 combos.

Those 119 are the all-in pile, the strong draws and the 12 combos of J9, which the short stack has just promoted to the pile. The 46 that check are the overcards that bluffed the flop (AK, AQ and KQ).

As the caller their flop looks very different. Say they called your button open from the big blind:

J♥8♥3♣

They check all 154 combos. Bet 2/3 pot and 42 go all in.

Those 42 are 36 strong top pairs and better and 6 strong draws. The 4 bare flush draws call and 108 fold. Bet 1/3 pot instead and 42 still jam, 46 call and 66 fold.

How to exploit them

Respect the all-in. A jam, a check-raise all in or a bet-then-jam is the all-in pile and nothing else. It's never a bluff. Fold one-pair hands that can't beat top pair, good kicker, unless the pot odds are very good and the board has a lot of draws.
Bet half pot or more to fold their weak hands. Middle pairs, bottom pairs and a bare flush draw on the turn call only a 1/3-pot bet. Half pot pushes them out. Weak top pair folds too while the stack is deep next to the pot; once less than three pots are left (the turn after a half-pot or bigger flop bet and call) it jams instead, so bet that turn only with a hand that can stand the all-in.
When they check as the raiser, bet. Their strong hands would have bet, so a check means a middle or bottom pair, a bare flush draw or nothing. On the turn it also means the overcards that bluffed the flop; the J9 combos that checked a deep turn now bet.
When they check as the caller, bet only hands that can stand an all-in. Their check hides their strong hands as well as their weak ones. Check back your medium hands.
Raise their c-bet only with the all-in pile yourself. Raise their flop bet on J-8-3 and 107 of their 165 betting combos go all in, 58 fold: two-thirds of the hands that bet the flop stack off.
Fold to their river bet with medium hands. They bet the river only with the all-in pile, and they don't bluff there.
Don't 3-bet them light. Their answer is all in or fold. 3-bet only hands happy to call 40 big blinds.
In your reads, watch their role: as the raiser a flop check removes the all-in pile; as the caller it hides it. Once they jam, paint only the all-in pile and count how much of it is draws.

Here's a read on their check-raise all in on J-8-3 with two hearts, from their big-blind call:

AAAKsAQsAJs−ATsA9sA8sA7sA6sA5sA4sA3sA2sAKoKKKQsKJsKTsK9sK8sK7sK6sK5sK4sK3sK2sAQoKQoQQQJs−QTsQ9sQ8sQ7sQ6sQ5sQ4sQ3sQ2sAJoKJoQJo+JJJTsJ9sJ8sJ7sJ6sJ5sJ4sJ3sJ2sAToKToQToJToTT−T9sT8sT7sT6sT5sT4sT3sT2sA9oK9oQ9oJ9oT9o9998s97s96s95s94s93s92sA8oK8oQ8oJ8oT8o98o8887s86s85s84s83s82sA7oK7oQ7oJ7oT7o97o87o7776s75s74s73s72sA6oK6oQ6oJ6oT6o96o86o76o6665s64s63s62sA5oK5oQ5oJ5oT5o95o85o75o65o5554s53s52sA4oK4oQ4oJ4oT4o94o84o74o64o54o4443s42sA3oK3oQ3oJ3oT3o93o83o73o63o53o43o3332sA2oK2oQ2oJ2oT2o92o82o72o62o52o42o32o22

in both− they have, you left out+ you included, they don’t have

Their real range here: 42 combos.

The read kept JJ, which they would have 3-bet, and missed the strong draws: T9s, QhTh and AhTh.

What this leak is worth. Real mistakes, but a 40bb stack caps what you can win. 3-bet their button open with a normal size and 83% of it folds; the rest shoves, and nothing calls.

What their bet sizes tell you

Nothing about the hand. Three-quarters of the pot on a dry board and the full pot otherwise, on every street, with a set and with two overcards alike. The only raise they ever make is all in. Read the pile, not the size.