The SB accounts for roughly a sixth of all hands and almost always plays at a loss. For a strong reg at NL50–NL200 that is −12 … −25 bb/100, for an average one noticeably worse. The difference between them is made almost entirely of one decision: what to do with hands that are too good to fold but not strong enough for a confident 3bet. That is, roughly half the hands you get dealt in the SB.
Why a call from the SB is expensive
By calling from the SB you create the worst spot in poker: out of position against the opener, with a player in the BB behind you who gets an excellent price to squeeze or call. Three things work against you at once.
- Equity realization. Out of position a hand realizes noticeably less of its equity than in position. The medium hands you most want to call with get the least of all.
- The BB behind you. Every call opens a cheap entry or a squeeze for the BB. Against a squeeze your hand usually folds, and the dead money is gone. You paid for the ticket and left before the film started.
- Rake. A three-way pot at micro stakes is raked noticeably, and your share of it is less than a third.
That is why solver strategies in the SB against a late-position open are built around the 3bet: a wide 3bet, a narrow or zero call. The smaller the open size and the higher the rake, the stronger the tilt toward "3bet or fold".
When a call is justified
A call from the SB is not a mistake in itself. It becomes reasonable when at least two of three conditions hold:
- The open is small, two bb or less, and the price of the call is good.
- The BB is passive: rarely squeezes and rarely defends, so multiway pots are not waiting for you.
- The hand realizes equity out of position decently: medium and small pairs, strong suited connectors, while not being so strong that a 3bet is obvious.
At NL200 fast-fold against an average pool these conditions are rarely met. At NL10 at regular tables with passive BBs, more often.
What to check in the database
The positional report will show the overall SB minus, but the decision hides deeper. Look at three cuts.
3bet and call frequency from the SB against BTN and CO opens. Compare not with a "norm" but with the solver and the top regs at your stake for the same open size. If the call is noticeably more frequent than the 3bet, that is the first signal.
Result by hand category after the call. Separately pairs, suited connectors, offsuit broadways, suited Ax. If a category systematically does worse than a plain fold, that is a finding with a price in bb. Usually offsuit broadways and weak Ax surface first, called "because folding feels bad". It starts to feel bad later, on the turn.
How often the BB enters after your call. If the BB squeezes against you more often than the pool average, part of your calls turn into direct losses before the flop.
What is usually found
In the databases of NL25–NL100 regs two variants come up most often.
The first: the call is too wide. Hands like KJo, QTo, A8o–A5o call a BTN open and then give up on the flop or turn. The price of such a finding over a 200,000-hand database easily reaches 0.5 bb/100 of overall winrate. KJo from the SB is a hand that looks like a picture card and plays like a seven.
The second, less visible: the 3bet is too narrow and value only. A BTN open gets a 3bet only from JJ+ and AK, everything else folds. The BB and BTN read this quickly, and the SB stops collecting the pots a solver strategy takes regularly. This finding costs less in bb, but it also makes your 3bets readable in every other spot: a thousand hands later the whole table knows that your SB 3bet is an announcement of a premium.
A simple rule for checking
Take all the hands where you called from the SB against a late-position open and look at how much they brought relative to a fold. If the number is negative on a sufficient sample, split by hand category and move the weakest into a fold or a 3bet. This is one of the few places in a database where a fix shows quickly: the spot is frequent, the decision is preflop, the sample fills within a month.