The wrap is a deception pattern. The ball carrier passes the ball outward and then loops around behind the receiver to take the ball back on the other side.
The mechanics are straightforward. Carrier A passes to receiver B, and then immediately runs an arc behind B. B carries the ball one or two steps and then passes back to A, who is now on the outside and has a clean running lane into the space the defense has just vacated. The defender originally marking A is left committed to B. The defender who would have marked A's new line is usually a half-step late because they were tracking the ball.
The wrap is only effective if the first receiver runs square and forces defenders to respect the possibility of a direct attack. If B catches and just waits for the return pass, the defense never commits and the wrap collapses into an obvious pre-set move.
The wrap works because defenders track the ball. When A passes to B, every defender's eyes follow the ball, and A becomes effectively invisible for half a second — long enough to slip around the back of B and reappear in a new lane.
Where it sits in a set: usually touches three, four, or five, when the defensive line is committed and tracking the ball laterally. It is less effective early in the set, when defenders are fresh and reading the whole field instead of chasing the ball.
The most common failure modes are forward passes (when A loops around they are already moving forward of B, and the pass back must respect that), B passing back too early before A has cleared the line, A running too flat so they do not get the depth advantage, and the defense reading the wrap and sliding to cover.