Rob Arthur writing for FiveThirtyEight:
MLB has denied making any intentional changes to the baseball, noting that testing finds the baseball still within established standards. But those specifications are extremely wide, allowing for massive variation in fly ball distance and corresponding shifts in home run rates. If MLB only rejects balls when they lie outside of the standards, there could be wild differences in air resistance between pairs of baseballs.
And we can measure how much air resistance is exerted on a given ball using MLB’s pitch tracking system. By measuring the loss in velocity from a pitcher’s hand to home plate, I calculated the drag coefficient of each pitch thrown in baseball since 2008. Drops in air resistance coincided with jumps in home runs, with drag especially falling for the average pitch this year. My study and a follow-up have demonstrated that this reduced drag could be to blame for some of MLB’s recent home run surge.
The home run explosion can’t be exclusively attributed to changes in shape and size of the baseball. The science will suggest drag on the ball differs greatly depending on the ball’s shape, but the other major variable is the player’s swing. Buster Olney for ESPN (scroll down a bit to the “Launch angle hitters…” section):
A really smart executive asked a really smart rhetorical question the other day as he discussed the high rate of home runs and strikeouts: “If a hitter trains himself to angle his swing upward, what is the highest pitch he can consistently reach within the strike zone?”
“If you’re talking about getting to the ball with an angled swing,” the executive continued, “the highest -- the highest -- might be mid-thigh, or at the groin.”
Players are selling out for the double or home run and have recognized they derive more of their financial value from total bases and less from putting the ball in play.
If baseballs are consistently juiced and if players are altering their swings to hit more doubles and home runs, so be it. Let the game evolve at its own pace.
This is why I love baseball. Statistics are spread out over such a large sample size, meaning players generally move towards their average. Having a great season in baseball, I believe, is more difficult than in any other sport on the planet. I mean, how many one-hit-wonders have we seen in the NFL over the last decade?