The Red Sox are hitting a different ball
The April weather only partially explains the offensive decline in baseball. The biggest issue might be the baseball itself.
As former Red Sox player and current NESN analyst Will Middlebrooks explained, players have noted that the balls used this season have noticeably higher seams. MLB might have done this intentionally to make it easier for pitchers to grip the ball after they started cracking down on the usage of sticky stuff to artificially improve spin rates.
Regardless of their intent to alter the ball, the change has had a notable impact on run production. Higher seams means the cover on the ball isn’t pulled as tightly. A tighter cover makes the ball harder, allowing it to travel further. The raised seams also create more air resistance.
These might seem like relatively minor differences but even a slightly softer ball that is slowed by increased drag on the higher seams could turn a home run into a routine fly out.
Strikeout rates haven’t spiked since last year. Boston’s 22.0 K% is actually slightly down from 22.6% last year. The decline in offense is primarily based on the balls in play. The Red Sox were second in the majors with a .309 BABIP last year, which isn’t unusual since the inviting green wall in Fenway Park’s left field helps turn balls that would be an out in many parks into a hit. This year, Boston is well below-average with a .270 BABIP.
The Red Sox have been a bit overly aggressive at the plate. They are swinging at pitches outside of the zone too much and they are the worst in the majors at drawing walks with a 6.3 BB%. Those are clearly factors in Boston’s lack of production but they are only part of the story. The Red Sox are putting the ball in play at a higher rate than last year and the steep decline in BABIP is influenced by the alterations to the baseball.