But we established there was a moderate correlation... which doesn't tackle the rest of the problem, that Mauer struck out more in 2014 than he had in any previous season while also hitting the ball more softly than any point in his career. BABIP and hard hit is a correlative argument but it still doesn't explain why Joe missed the ball so often and so rarely squared up. And, yes, his 2013 season saw an increase in strikeouts... but the rest of his stats, even the underlying ones, stayed strong. He posted one of the highest OPS seasons of his career with that strikeout rate because those underlying stats stayed at his career norms (his BABIP was a bit high but only .040 over his career rate, nothing even close to explaining a .150 OPS drop). So what changed? People who argue the concussion wasn't the most significant impact on his career throw out "shifts" and "harder-throwing pitchers" but that doesn't pass the smell test. It's not as if shifts and harder-throwing pitchers showed up overnight. Those are gradual game changes not implemented by every team to this day, yet it's used as a reason why Mauer went from great to pedestrian in ten months.