Lazio 2, Milan 2 — the lay was paid by the one result a conventional betting slip treats as a non-event. Today Napoli are 1.99 to lay, which is the pivot almost exactly: €990 at risk to win €980.

Lazio 2, Milan 2. The lay of Milan was paid by the result most betting slips treat as a dead loss, and it returned €980 against a liability of €1,220 that never came due. Twelve positions closed: five wins, seven losses, minus €840 on €11,450 of risk. The deficit has halved in an afternoon, which is worth noting mainly for what it says about variance rather than about method — the same swing runs the other way just as easily, and did, four days ago. The number that matters more is this one. Of the five wins on this book, four were paid by a draw and one by an upset. Laying the favourite is not a bet on the underdog; it is a bet on the third result, and yesterday was the fourth time that result has arrived and been collected. The mechanism is doing what the method says it does, in a book that is nonetheless still down money.

Today the book lays Napoli at the Maradona at 1.99, which is as close to the 1.98 pivot as a price can sit. The liability is €990 against a win of €980: for practical purposes the position is symmetric, we stand to lose ten euros more than we stand to gain, and everything turns on frequency rather than on shape. Break-even is 50.3% — Napoli have to fail to win slightly more often than half the time. Strip the margin off the back column — 1.98 Napoli, 3.65 the draw, 4.4 Bologna, an overround of 100.6% — and the fair line reads 50.2% / 27.2% / 22.6%. The two results that pay us add to 49.8%. We need 50.3%. Four tenths of a point against us, roughly €9 of negative expectation per €1,000. The case for the price being generous is Napoli’s September. Allegri’s side have lost their last three across all competitions, two of them in the league, and are without seven players including Meret, Anguissa and McTominay. Bologna are the other kind of problem: winless in three, a single draw, two goals scored in total. A team that neither scores nor collapses is a description of a team that produces the third result — and they took four points off Napoli last season, winning both league meetings.

The honest counter is the home record and the price itself. Napoli have won nine of their last twelve at home against Bologna, and a side that has just lost three in a row is, more often than the eye suggests, a side about to win one. The market has already marked Napoli down from where they would have been priced a fortnight ago; 1.98 for this squad at the Maradona is a considered number, not an oversight. Bologna’s two goals in three matches cut against us as much as for us — a team that cannot score loses 1–0 at least as readily as it draws 0–0. And the geometry today is honest but gives nothing away: at 1.99 there is no cushion in either direction. We are four tenths of a point short of the arithmetic working. Twelve closed positions with a minus in front of them is still a number too small to draw a line through, and it will be too small tomorrow as well.