With 10:32 to play in the third quarter of a Week 7 game between the Kansas City Chiefs and San Francisco 49ers, Brock Purdy settled under center with his offense on the opponents’ 1-yard line. Purdy tapped his helmet, which caused fullback Kyle Juszczyk to also tap his helmet, likely to confirm the play to running back Jordan Mason was still on. The 49ers had their backs in the I-formation, with one tight end to the left and two tight ends to the right, all of them on the line of scrimmage.
Most Chiefs defenders looked like track runners at the starting line of the 100-meter dash. Their legs were twitching and all six down linemen were rocking up onto their fingers in preparation for a short-range collision to try to prevent San Francisco from taking the lead. At that moment, the 49ers were the league’s seventh-best offense in the NFL in terms of EPA per play, while the Chiefs were the 10th-best defense along with the 10th-best red zone defense.
