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Activity Number: 342 - SPEED: Sports to Fire: Fascinating Applications of Statistics
Type: Contributed
Date/Time: Tuesday, July 31, 2018 : 10:30 AM to 12:20 PM
Sponsor: Section on Statistics in Sports
Abstract #328810 Presentation
Title: The Home Run Spike of MLB 2017: Drop in Quality of Pitch (QOP) Is a Missing Factor
Author(s): Jason Wilson*
Companies: Biola University
Keywords: baseball; sports; sabermetrics; QOP; quality of pitch

MLB news at the end of 2017 buzzed with discussion of the spike in home runs (4909 in 2015, 5610 in 2016, and 6105 in 2017). The two most prominent theories were a change in the ball (which MLB denied) and more batters swinging at an upward angle. The other main possible factor, pitching, received very little attention. However, using our Quality of Pitch (QOP) statistic (, the league average QOP dropped for every major pitch category, including 11% for Four-Seam Fastballs, 2% for Sinkers, 4% for Cutters, and 3% for Sliders. In this presentation, we will present evidence that although pitchers threw faster in 2017, it was at the loss of vertical break and command, which supports the increase in home runs. In addition, we will include an assessment of the MLB change from SportVision to Trackman PITCHf/x data in 2017 that concludes any differences are not substantial enough to mask the signal of the large drop in QOP.

Authors who are presenting talks have a * after their name.

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