Major League Baseball is testing new defensive positioning rules in the Arizona Fall League to address declining offensive production and increase base hits. According to FanGraphs, sources indicated the league's motivation is to determine if further limiting where defenders can stand will create more base-hit action and positively impact the game's aesthetics.
The initiative follows a broader trend of decreasing run scoring and rising strikeouts across the sport. While MLB previously restricted infield shifting, requiring shortstops and second basemen to remain on their side of second base, data shows this change had limited impact on total hits. Although league-wide batting averages on ground balls surged to the mid-.240s, the total number of hits remained flat because hitters increasingly opted for fly balls. Front offices have prioritized players capable of high-quality contact in the air, as outcomes on fly balls and line drives have historically offered significantly better batting averages and slugging percentages than ground balls.
However, advanced analytics and Statcast data have allowed teams to counter this strategy by positioning fielders more effectively. Defensive alignments have become so precise that success rates on fly balls and line drives have dropped dramatically. League-wide batting averages on balls in the air have fallen by 35 points from the 2019 season and roughly 20 points from 2018 or 2021. This defensive efficiency was evident in a recent National League Championship Series game between the Los Angeles Dodgers and Milwaukee Brewers. In that matchup, Freddie Freeman hit a changeup with a 106.4 mph exit velocity and a 22-degree launch angle toward the right-center gap. Statcast data indicates that balls with those characteristics are hits 84% of the time. Despite this, Milwaukee right fielder Sal Frelick was positioned to catch the ball without diving, turning a potential bases-clearing double into an out.
The new rules being tested in the Arizona Fall League aim to counter this defensive optimization. Dark green hash marks have been painted on the outfield grass and at points where the infield dirt meets the outfield grass. Defenders must stand within a certain distance of these hash marks when a pitch is thrown. This alignment forces infielders to play straight up, positions corner outfielders closer to the foul lines, and places the center fielder more shallowly than typical major league positioning.
The Hawkeye system is being used to monitor player locations relative to these painted anchor points. LED boards visible from the field display whether players are in compliance with the location restrictions. If adopted, these rules would require outfielders to cover more ground, increasing the importance of athleticism and skill. The changes could also allow faster hitters to push balls into gaps for extra bases, potentially altering the strategic balance between pitching and hitting in a sport where contact has become increasingly difficult.