Major League Baseball is testing a new experimental rule in the Arizona Fall League that restricts how outfielders position themselves during at-bats. The trial, which is currently limited to games played at Salt River Fields in Arizona, requires outfielders to play "straight up" rather than shifting their position based on the specific hitting tendencies of the batter.
The league is conducting the experiment to determine if limiting defensive shifts will increase offensive production, specifically doubles and triples. The Arizona Fall League has previously served as a testing ground for other rules eventually adopted by the major leagues, including the pitch clock, larger bases, and restrictions on infield shifts.
Under the experimental system, players utilize a small video board located above home plate to confirm their positioning. If an outfielder is standing in the designated "straight up" area, the board displays a green "O." If the player shades too far in any direction or stands at an incorrect depth, a red "X" appears to signal they must move. Salt River Fields is the only venue used for the test because it is equipped with tracking technology similar to that used in Major League stadiums.
For the players, the concrete day-to-day change involves increased physical demand and altered defensive play. Washington Nationals prospect Teo Banks noted that the restrictions force outfielders to play more shallow, meaning their first move on most fly balls is to run backward. While this has effectively eliminated "bloop" singles, it has led to an increase in extra-base hits. In one experimental game between Scottsdale and Salt River, the teams combined for five triples, setting a new Arizona Fall League record.
The trial also introduces new positioning requirements for infielders when no runners are on base. The league declined to provide an official comment on the experiment, noting that any potential implementation in the Major Leagues would be years away. The current Arizona Fall League season began on Oct. 3, 2026, and the results of this data collection will likely inform future discussions between MLB and the competition committee regarding permanent rule changes. No specific deadline for a vote or further implementation has been reported.