Hitting around the shift: Evaluating batted-ball trends across Major League Baseball

Abstract

The infield shift has negatively affected Major League hitters who formerly thrived on ground balls through the gaps in the infield. Nearly a quarter of plate appearances during the 2019 season featured infield shifts, up from 13.8 percent just three seasons prior. I analyzed both the evolution of shift implementation and whether batters hit differently with and without the shift using hierarchical Bayesian regression methods on both pitch-level and batter-tendency data from 2015 to 2019. Since most of the recent talk surrounding the infield shift has been related to a drastic increase in fly balls and players hitting over the shift, I looked specifically at adaptation on the ground. Not a single batter was found to have had a significant difference between their batted-ball distributions for either a given season or throughout the entire five-year period, suggesting the increase in shifting is unlikely to end in the near future.