In American football, a pass rush is an attempt by the defensive team to disrupt the offense and prevent the quarterback (QB) from completing a pass. Existing metrics for assessing pass rush performance are either discrete-time quantities or based on subjective judgment. Using player tracking data, we propose STRAIN, a novel metric for evaluating pass rushers in the National Football League (NFL) at the continuous-time within-play level. Inspired by the concept of strain rate in materials science, STRAIN is a simple and interpretable means for measuring defensive pressure in football. It is a directly-observed statistic as a function of two features: the distance between the pass rusher and QB, and the rate at which this distance is being reduced. Our metric possesses great predictability of pressure and stability over time. We also fit a multilevel model for STRAIN to understand the defensive pressure contribution of every pass rusher at the play-level. We apply our approach to NFL data and present results for the first eight weeks of the 2021 regular season. In particular, we provide comparisons of STRAIN for different defensive positions and play outcomes, and rankings of the NFL's best pass rushers according to our metric.

翻译：在美式橄榄球中，冲传是防守方试图破坏进攻方并阻止四分卫完成传球的策略。现有评估冲传表现的指标要么是离散时间度量，要么基于主观判断。利用球员追踪数据，我们提出了STRAIN——一种新颖的指标，用于在国家橄榄球联盟（NFL）中以连续时间、单档进攻层面的尺度评估冲传球员。受材料科学中应变率概念的启发，STRAIN是一种简单且可解释的衡量橄榄球防守压力的方法。它是一个直接观测的统计量，由两个特征构成：冲传者与四分卫之间的距离，以及该距离缩小的速率。我们的指标对压力具有出色的预测能力，且随时间保持稳定。我们还为STRAIN拟合了一个多层模型，以理解每一档进攻中每位冲传球员对防守压力的贡献。我们将该方法应用于NFL数据，并展示了2021年常规赛前八周的结果。特别是，我们比较了不同防守位置和进攻结果下的STRAIN值，并根据我们的指标给出了NFL最佳冲传球员的排名。