Why a six-point teaser is a bet about two numbers

A teaser moves every leg in your favour by a fixed amount at a worse price. Six points is the standard football version, and the entire question is whether those six points cross both 3 and 7.

Those two numbers hold roughly a fifth of all NFL margins between them. Moving a line across both converts a large block of previously losing outcomes into winning ones; moving it across neither converts almost nothing and costs the same.

The price still has to be beaten. A two-leg six-point teaser typically needs about 72 per cent per leg to break even, and crossing both key numbers is what makes that reachable rather than what makes it free.

Here is the catch. A leg that crosses neither key number is packaged identically to a leg that crosses both, at the same price. The product does not distinguish them and the arithmetic does.

What to do with it. Check what each leg crosses before taking a teaser, and refuse the ones that cross nothing.