标题： 摆动，快速与缓慢：解释棒球击球跟踪指标的变化 显示英文标题

标题： Swinging, Fast and Slow: Interpreting variation in baseball swing tracking metrics

摘要： 2024年，美国职业棒球大联盟发布了新的棒球追踪数据，报告了击球时每个击球动作的棒球速度和击球长度。 虽然令人兴奋，但这些数据在解释上存在挑战。 击球手击球的时间相对于投球决定了测量点相对于完整击球路径的位置。 击球指标与击球结果之间的关系受到击球手识别投球能力的混淆。 我们引入了一个解释棒球追踪数据的框架，在该框架中，我们首先使用具有随机截距和随机斜率的贝叶斯分层偏正态模型，根据球数和好球数以及投球位置估计击球手的意图。 这得出击球手特定的计数对击球指标的影响，我们通过工具变量回归利用这些影响来估计棒球速度和击球长度对接触和力量结果的因果效应。 最后，我们通过将一次击球行为建模为马尔可夫链，评估由于棒球速度导致的接触与力量之间的权衡。 我们得出结论，随着坏球数量的增加，击球手可以通过降低棒球速度来减少三振出局率，但减少的力量的权衡大致抵消了对平均击球手的好处。 显示英文摘要

摘要： In 2024, Major League Baseball released new bat tracking data, reporting swing-by-swing bat speed and swing length measured at the point of contact. While exciting, the data present challenges for their interpretation. The timing of the batter's swing relative to the pitch determines the point of measurement relative to the full swing path. The relationship between swing metrics and swing outcomes is confounded by the batter's pitch recognition. We introduce a framework for interpreting bat tracking data in which we first estimate the batter's intention conditional on ball-strike count and pitch location using a Bayesian hierarchical skew-normal model with random intercept and random slopes for batter. This yields batter-specific effects of count on swing metrics, which we leverage via instrumental variables regression to estimate causal effects of bat speed and swing length on contact and power outcomes. Finally, we valuate the tradeoff between contact and power due to bat speed by modeling a plate appearance as a Markov chain. We conclude that batters can reduce their strikeout rate by reducing bat speed as strikes increase, but the tradeoff in reduced power approximately counteracts the benefit to the average batter.