Big League Balls in Minor League Stadiums

Some Triple-A players have seen their home run numbers spike early this season. (via Minda Haas Kuhlmann)

There is a new baseball in Triple-A, which now has the same one used in the majors, and it’s obvious the game there has changed. I’ve spent the last four years as a semi-frequent occupant of the press box in Louisville, and until this year, I’d grown accustomed to watching balls die in the outfield, especially in left. But not now. Last year, the Bats hit their 50th home run on June 23. This year, they hit it on May 23. No, the Triple-A season did not start a month earlier this year.

In 2018, International League teams scored 4.16 runs per game and Pacific Coast League teams scored 4.97 runs per game. This year, it’s 5.20 and 5.65, respectively. Yeah, the ball is carrying farther. The Bats have had a couple of players with breakout power years as at least a partial result of the new ball. Josh VanMeter, in 131 plate appearances, was one homer short of his career best in this, his seventh season as a pro, when he was called up by the Reds. Notably, he’s made changes to his approach that can be seen in his second-half numbers from last year, but he never had shown power on this level.

Brian O’Grady has had similar results. His 14 homers in 189 PAs match his career high. He also hit 14 last year — in 386 PAs. As with VanMeter, there were other adjustments, but that didn’t account for all of it. “There’s definitely times you can notice,” O’Grady told me. “I hit a double the last night that went farther than I thought it was gonna.” When I talked to him, he clearly liked the new ball. “I think the ball plays more true. I think before there were a lot of times when guys hit balls and they went like nowhere. Now, if you hit it, you get rewarded for it.”

With all this homer talk, it’s important to note that however juiced the ball might seem in the majors, it looks even more juiced in Triple-A. Last year, pitchers in the International League gave up 0.8 homers per nine innings. This year, it’s 1.3. That’s like jumping from 1990 to 2019 in one season in terms of major league home run rates.

I was interested in hearing some perspective from the other side of the baseball, so I sought out Jeff Fassero, who is the pitching coach for Louisville and who had a 16-year major league career of his own that almost perfectly aligned with the offensive explosion across baseball. His take was absolutely not what I expected.

“I’d rather throw this ball [than the minor league ball],” he said. “The seams are better. The ball spins better. I’ve seen better spin. Better breaking balls. It feels better in your hand. This ball breaks better than the minor league ball. Obviously, it’s carrying better, but if you execute pitches, you won’t give up home runs.” He did note that pitchers sometimes become “afraid of contact” with the new ball.

The carrying farther part is obvious and easy to check, as I’ve shown. It’s also what everyone is focusing on. But the thing about spin is harder to check. Spin data exists for minor leaguers, but its public availability is sporadic, to say the least. This is the part where I spend lots of time clicking around trying to figure out how to confirm or rule out what Fassero said. Fassero has more than enough experience for me to believe what he says about the seams, but I can’t be sure it’s changing game results until I see data.

While Triple-A is using the major league ball this year, the rest of the minors are still using the (presumably) unchanged minor league ball. So I started comparing league stats over the last few years. And this is where I hit pay dirt. Up to the moment of this writing, Triple-A strikeouts per nine are up about 9%, and walks per nine are up about 18%. The other minor league levels show some change in strikeouts but no comparable change in walks. If a ball spins better, one way that might show up in the data is in walks and strikeouts, especially in Triple-A, where there are a lot of pitchers with pretty refined repertoires.

Major League Baseball always holds that the baseball is the same. We know now it isn’t: multiple studies have shown it changes from season to season. But while the focus always has been on the increase in home runs, I’ve never seen anything suggesting the increase in strikeout and walk rates might be attributable, at least in part, to the ball. The presumption always has been that those changes were due to a change in approach: harder fastballs, different hitting philosophies. What’s happening in Triple-A suggests otherwise.

There has been, it should be noted, a steady rise in strikeouts and walks over the years in the minors that mirrors what’s happened in the majors, but the sudden spike this year tells us the ball can also affect these things. Imagine a game with a third fewer homers, a fifth fewer walks, and a tenth fewer strikeouts. That seems to be about the size of the effect the ball is having in Triple-A.

We’re only about 40% of the way through the minor league season, so the numbers aren’t conclusive yet, and there’s still a lot of stuff to be looked at by people who know a whole lot more math than I do. But what we do have here is a very real chance to look at a largely stable environment with one clear variable: the ball. MLB wants to say the ball never changes. It wants to say it has no control over the changes happening in the game. Introducing the major league ball to Triple-A changes all that. It’s completely clear the style of play is largely dictated by the ball.

I asked Fassero if he noticed any changes in the ball over the course of his career. He said he hadn’t, “but you weren’t really looking for it. If you went back and got a ball from 1992, you could see if the leather is any different or whatever.” I wonder if maybe it isn’t past time for this. These baseballs are out there. They exist. I’ve never caught a foul at a major league game, but I have a nine-year-old minor league ball in my desk drawer someone gave my daughter when she was a baby. Many of us have these, don’t we?

MLB knows the ball is different but won’t own up to it. It seems as though it may be actively choosing to favor the current style of play. For those of us who are curious, there are two methods we could use to learn about how the ball affects play. The first is to look at how numbers change across Triple-A this year, especially once the season is over. The other is for some researchers to start gathering up as many baseballs from as many different years as they can find and start taking measurements and performing experiments. We can get definitive answers. We just have to look.

A Hardball Times Update
Goodbye for now.

Jason teaches high school English, writes fiction, runs a small writing program and writes about education and literature. He also writes for Redleg Nation and both writes and edits for The Hardball Times. Follow him on Twitter @JasonLinden, visit his website or email him here.
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4 years ago


“5. We conducted laboratory testing of 15 dozen unused Major League
baseballs from 2013 to 2017, and a total of 22 dozen game-used Major
League baseballs from the years 2012-2017, to measure properties of
the baseball, including properties that were not measured by Rawlings
in the normal course.

6. We devised and conducted novel tests of the baseball at Washington
State University to attempt to identify the factors that were causing
baseballs manufactured in 2016 and 2017 to have lower drag coefficients
than baseballs manufactured prior to 2016.”

D.K. Willardsonmember
4 years ago

Great article. I’ve been keep a spin/drag ball model (MLB ball only) for the past few years. It was flashing a big change last year (increased drag) – confirmed with distance and HRs down significantly. Then, what do you know, this year, the ball appears to be playing “in-between” low-drag-2017 and high-drag-2018. If all these changes are purely coincidental, I would be VERY surprised.

4 years ago

Trevor Bauer is going to love these changes.

4 years ago

i am still astonished that organized baseball has had different quality baseballs for use in the minor leagues. My game is golf, which I have played for over 70 years and have been a PGA Member for over 50 of those years. I and every amateur golfer at every course in the world was always able to play with exactly the same balls that are used on every Professional Tour in the world. A young man I coached played on the lower levels of the PGA Tour in Latin America, Canada and China for 5 years. He was provided with the best equipment at no cost and the tournaments were held at the finest country clubs in every city. The players were treated extremely well with lavish food spreads often included, free transportation from the host hotel and other amenities. MLB should be embarrassed by the way the minor leagues are run, paying the players next to nothing then running a second rate operation with inferior equipment. It is hard to believe.