also: double team run · power without a puller
A downhill run built on double teams with nobody pulling. Coaches disagree about whether it is a gap scheme, a zone scheme, or its own thing, and that argument reaches the NFL.
2 meanings, all below. Jump to the one you heard.
A downhill run with two double teams inside and no pulling linemen. The line's job is vertical movement rather than displacement sideways, and the back reads the linebackers to decide where to go, so the play has a gap scheme's physicality and a zone play's read.
What it buys is power without the exposure a pull creates. Nobody leaves, so there is no vacated gap to hinge for and no puller to be beaten to a spot.
inside zone, power, isoDuo gets classified three different ways by serious people. Called gap scheme because it is downhill and double-team based, called zone because the linemen are not blocking named men and the back is reading, and called its own category because it fits neither cleanly.
This entry does not settle it, and that is the honest position rather than a dodge. What a new coach needs to know is that hearing duo described two different ways in two different rooms does not mean somebody is wrong.
gap scheme