Traditional assessments of tackling in American Football often only consider the number of tackles made, without adequately accounting for their context and importance for the game. Aiming for improvement, we develop a metric that quantifies the value of a tackle in terms of the prevented expected points (PEP). Specifically, we compare the real end-of-play yard line of tackles with the predicted yard line given the hypothetical situation that the tackle had been missed. For this, we use high-resolution tracking data, that capture the position and velocity of players, and a random forest to account for uncertainty and multi-modality in yard-line prediction. Moreover, we acknowledge the difference in the importance of tackles by assigning an expected points value to each individual tree prediction of the random forest. Finally, to relate the value of tackles to a player's ability to tackle, we fit a suitable mixed-effect model to the PEP values. Our approach contributes to a deeper understanding of defensive performances in American football and offers valuable insights for coaches and analysts.

翻译：传统美式橄榄球擒抱评估通常仅考虑擒抱次数，未能充分考量其比赛情境及重要性。为改进此问题，我们开发了一种通过预防预期得分（PEP）量化擒抱价值的指标。具体而言，我们将擒抱的实际攻防线位置与假设擒抱失败情境下的预测攻防线进行对比。为此，我们采用记录球员位置与速度的高分辨率追踪数据，并运用随机森林模型处理攻防线预测中的不确定性与多模态特征。此外，我们通过为随机森林中每棵决策树的预测分配预期得分值，以区分不同擒抱的重要性差异。最后，为建立擒抱价值与球员擒抱能力的关联，我们采用适合的混合效应模型对PEP值进行拟合。本方法有助于深化对美式橄榄球防守表现的理解，并为教练与分析人员提供有价值的洞见。