Philadelphia Phillies second baseman Luis Arraez has regressed offensively since joining the organization. In his first 41 games in Philadelphia, he has a .284 batting average, a .320 on-base percentage, and a .387 slugging percentage.

These numbers are 30% worse than his tenure with the San Francisco Giants. During that tenure, he hit .325 with on-base and slugging percentages of .362 and .443, respectively.

The statistical difference between his tenures in both organizations likely relates to changes in his swing approach. Since joining the Philadelphia Phillies, Luis Arraez has opened up his stance significantly.

Over his first 41 games with the organization, he has a 32-degree open stance. That is five degrees higher than in San Francisco, where he had a 27-degree open stance.

Luis Arraez is also waiting longer to make contact with the baseball. Over his first 41 games with Philadelphia, his average intercept point has been 2.9 inches behind home plate. His intercept point in Philadelphia is 1.7 inches deeper than in San Francisco.

These two factors make it look like Luis Arraez is more off balance. His right hip routinely points toward first base while his torso points toward third base.

These changes have contributed to him being under the ball more often on contact. Over his first 41 games in Philadelphia, he has been underneath the baseball 55 times. That is nine times more than his first 41 games in San Francisco.

Luis Arraez performed better at Oracle Park in San Francisco because he kept his body more aligned in one direction as he was about to hit the ball.

Because of these changes, he is hitting the ball with less force in Philadelphia. The average exit velocity has been 84.4 miles per hour, 2.6 miles per hour less than in San Francisco. If he can regain that alignment, his statistics are more likely to revert to what they used to be.