It's a very weird dynamic. The Sox have a very high BABIP, yet also have a lower AVG than xAVG, which is the opposite of what you'd expect. As the BABIP has gone up recently, the gap between xAVG and AVG has narrowed, but xAVG is still 5 points higher. It's like they're simultaneously having a lot of good luck on some batted balls and a lot of bad luck on others.
Also of note, xSLG is 61 points lower than SLG, so the bad luck on hard hit balls is hurting more than the good luck on all those ground balls is helping.