This is why people are wondering whether MLB is using a juiced baseball these days ...
| Season | Home runs per team, per game |
|---|---|
| 2017 | 1.26 |
| 2016 | 1.16 |
| 2015 | 1.01 |
| 2014 | 0.86 |
That's a steep upward trend when it comes to home runs on a league-wide basis. As well, that 1.26 figure from last season is an all-time record by a wide margin (breaking the 1.17 mark in 2000).
Part of what's going on is a widespread emphasis among hitters on elevating the ball via an increased launch angle. A bigger factor, however, appears to be structural changes to the baseball itself. The seams may be lower and tighter, and the ball may be bouncier and -- to hear some World Series participants tell it -- slicker.
MLB has countered that the contemporary baseball still falls within the normal ranges when it comes to official specs. Part of the issue, though, is that those normal ranges are fairly sprawling. In other words, two balls can satisfy those criteria and behave quite differently off the bat.
Now via Rob Arthur and Tim Dix of FiveThirtyEight.com comes the latest bit of evidence. Arthur and Dix arranged to have balls from after the 2015 All-Star break, when the home run surge truly began, X-rayed and examined by scientists from USC and Kent State. Here's a summary of what they found ...
Looking inside the balls and testing their chemical composition revealed that the cores of recent balls were somewhat less dense than the cores of balls used before the 2015 All-Star Game. The newer cores weigh about a half a gram less than the older ones, which might be enough to cause baseballs hit on a typical home run trajectory to fly about 6 inches farther. That alone is hardly enough to explain the home run surge of recent seasons, but when combined with previous research finding that baseballs began to change in other small ways starting around the same time, it suggests that a number of minor differences may have combined to contribute to the remarkable upswing in home run power we've witnessed since 2015.
Arthur and Dix's story also includes MLB's response to the new findings, so you'll want to give the piece a full reading.
In all, the evidence continues to mount that the ball is different and is the major factor in what's turning out to be the greatest home run era in baseball history. This of course doesn't mean what we're witnessing has conspiratorial underpinnings, but it's a reminder that the standards for baseballs are too permissive and, perhaps, too loosely monitored.
In the meantime, keep enjoying balls flying over fences.
