NFL teasers: the window most guides get wrong

A teaser moves the spread in your favour on every leg, and every leg has to win. The whole reason it can be a good bet in the NFL rather than a sucker bet is the key-number lattice: a six-point move can cross both 3 and 7, and those two numbers alone account for 24.11% of all final margins.

The window, and why the textbook one is wrong

Teasing a side at line L by k points converts every margin in the interval (−(L+k), −L] from a non-win into a win. That interval is open at the far end and closed at the near end, and both ends matter:

• a margin landing exactly on −(L+k) becomes a push after the tease, not a win — so the far key number is only half bought and does not count;
• a margin landing exactly on −L was already a push before the tease and becomes a win — so the near end does count.

Getting that backwards is what produces the familiar Wong window of favorites −7.5 to −8.5 and dogs +1.5 to +2.5. Work the arithmetic through properly and the 6-point window is favorites −8.5 to −7.0 and dogs +1.5 to +3.0 — half a point wider at both ends.

The two omitted rungs are not a rounding detail. −7.0 and +3.0 carry 1,561 of the 2,871 qualifying legs — more than half of them. A guide that states the textbook window is telling you to skip the majority of the market.

The price is the entire play

This is the part most teaser content skips. A 73.88% leg is a good bet or a bad one depending on a number the book chooses, and the range of prices in the wild spans both.

A two-team teaser needs both legs, so it wins 0.7388² = 54.6% of the time. At −110 that returns about +4.2%. At −130 — the standard two-team price at most US books — the same legs return about −3.4%. The identical bet flips from winner to loser on the price alone.

Three-team tickets are usually the better-priced version, because books tend to underprice the compounding. A three-teamer at +180 needs 70.95% per leg against the measured 73.88%.

Which size to buy

Six points is the famous size, but it is not automatically the right one. Three sizes carry a genuine key-number advantage. The test is not the raw win rate — bigger teases obviously win more legs — but what is left after subtracting the value of simply buying that many points.

The control column below is the qualifying window’s rate minus the rate of teasing an arbitrary line by the same amount, restricted to the same range of line sizes. That is the part the key numbers are actually contributing.

Read the last two columns together and the trap is obvious. A 13-point tease wins 85.80% of its legs, which looks superb — and its control is −0.48 points. The window is slightly worse than teasing a random line by thirteen. All of that 85.80% is “you bought thirteen points”, which is the one thing a book prices to the cent.

The mechanism is plain once stated. A six-point tease converts an interval holding 24.1% of all margins, and 3 and 7 are that interval. A thirteen-point tease converts thirteen points of mass wherever it starts, so which numbers it crosses stops mattering.

Practical rules

• Select on the consensus number, then shop. The window decides which games are worth teasing. Once a game qualifies, taking a better number is strictly better — a leg should never be refused because your book hung something generous.
• Check the price before the legs. At a two-team −130 these legs lose. Work out what your book charges for each size first, then pick the size, then pick the legs.
• Ignore 10 and 13-point offers however good the headline rate looks.
• Never tease a total. Totals have no comparable lattice — the most common exact total occurs on under 4% of games, against 24.1% for margins on 3 and 7 combined.

Common questions