Ever since the steroid era, baseball fans have been cautious about reading too much into unexpected leaps in player performance. Today’s jaded rooters assume that performance-enhancing drugs are to blame, somehow, whenever a player experiences a breakout or the league undergoes a transformation. So it’s no surprise that, with home runs flying out of parks at nearly an all-time high in 2016, many have reacted by assigning the responsibility to some undetectable new PED.After exhaustive consideration, my former FiveThirtyEight colleague Ben Lindbergh and I concluded that the most likely culprit for 2016’s home run explosion is a change to the construction of the ball.