How deep is a normal downswing?
The downswing always feels like the end of your edge. The maths says otherwise: for a thin win rate and big swings, a normal downswing runs deeper and longer than almost anyone expects.
The number nobody tells you
Expected downswing depth scales with your standard deviation squared over twice your win rate. Plug in a real 4 BB/100 edge and a 90 BB/100 standard deviation and you get normal downswings on the order of ten buy-ins. Ten. That is not tilt or a broken game, it is the distribution doing what distributions do.
Why knowing it matters
A player who knows their number rides the downswing out. A player who does not panics at buy-in three, jumps stakes to get it back, and turns variance into a real loss. The number is armour against your own worst instincts.
What to actually do
Drop down if your bankroll says so, shorten sessions to protect your A-game, review your hands to rule out a leak, and keep playing the same edge. The line bends back, but only if you are still in the game and still playing well.
Normal does not mean harmless
A normal downswing can still damage a bankroll if you sized the game badly. It can also damage decision quality if you keep using every lost pot as evidence that something is wrong. The useful distinction is not calm versus worried. It is expected versus unexplained. Expected downswings get bankroll discipline, shorter sessions and routine review. Unexplained results get a deeper leak search, table-selection audit and maybe a lower stake while the evidence catches up.
Build the rule before the stretch starts
The rule has to exist before the first bad week. Decide the buy-in floor that forces a drop, the number of hours before you reassess, and the study checks you run when results sit outside the expected band. If you write the rule mid-downswing, the rule will quietly become whatever your mood wants. A tracker helps by putting the same inputs in front of you every time: bankroll, stake, standard deviation, observed win rate and the size of the current drawdown.