The National Football League tracks athletes’ movement and positioning in each game through radio frequency identification tags inserted in players’ shoulder pads and inside the football. By analysing the tracking data of the first nine weeks of the 2022 season — made available for the National Football League Big Data Bowl 2024 — Nguyen and colleagues aimed to provide a more accurate metric for tackles. In particular, the dataset encompassed more than 5,500 plays by running backs, with several frames of each play labelled with a description.

For events labelled as a first contact or tackle, the team identified a contact window in which the defensive player was close to the opposing team’s running back. For each contact window, they calculated the change in the ball-carrier’s velocity between the first and last frame and distributed it evenly between each frame. Then, each frame-level value was shared equally between all defensive players in the respective contact window. Finally, the fractional tackle sums up the contributions of all frames of a contact window for a given defender.