Four Perspectives: How Do MLB and MiLB Balls Differ?

Pitchers need to get used to a different ball when they reach the big leagues. The variance is slight, but it is nonetheless noticeable. That was the opinion of four pitchers to whom I spoke, and facts back up their feelings.

According to a source within Major League Baseball:

  • The MLB ball is made in Costa Rica, and the MiLB ball is made in China.
  • The MLB balls cost more.
  • There are some differences in the materials, such as the kind of leather.
  • Tests are conducted, and the performance of the balls are in line with one another. Even so, major-league pitchers on rehab assignment are allowed to use MLB balls during their minor-league outings.

That last bullet point seems especially telling. Given the availability of that option, there is clearly a difference.

Here is what the handful of hurlers — all of whom pitched in both MLB and Triple-A last season — told me in mid September. Along with the physical feel of the spheroid, pitch movement and the carry of fly balls were also addressed.


On the Construction and Feel of the Ball

Ben Heller: “It seems like it’s a bit tighter in the big leagues. And the ball is slicker, too. The way they rub it down here makes it a little slicker in your hand, so I find myself trying to get a little moisture to counteract that.”

Jonathan Holder: “There are a little less seams here (in MLB). It’s also a little slicker, so it’s harder to get a grip, but I wouldn’t say I notice it that much. For instance, the college ball was completely different. They’ve changed it recently, but when I was [at Mississippi State], it had huge seams and didn’t move as much.”

Blake Parker: “It’s a completely different ball. The seams are tighter, and they’re smaller (in MLB). It seems like the ball in general is tighter, kind of how… the way it’s put together. Maybe it’s the way they wind it up on the inside? But you can feel the difference. It’s tighter, or maybe I could say it’s denser.”

Kirby Yates: “The seams are higher in the minors. Big-league balls, the seams are a little smaller and they’re wound a little tighter. It’s always been like that, and I’ve gotten used to it. When I come back up, or get sent back down, I already know how to adjust. It’s not like it’s a huge, drastic change, though.”

On Differences in Pitch Movement

Heller: “My fastball actually rides a little bit more. For whatever reason, it has more life to it in the big leagues than it does down in the minors. I feel like my slider moves less. The minor-league balls, with the bigger seams, give my slider a little more downward break. I can start it at the batter’s hip, or almost at his shoulder, and it will break down for a strike. With the big-league balls, if I leave my slider up at all… it seems like it just spins. I need to drive it down, and really finish it, to get that good break.”

Holder: “I think I’ve seen a slight difference. The ball might move a little more here. I think it makes my breaking stuff a little better. Fastballs — if you’re a sinker guy, which I’m not — might be helped moving down in the zone.”

Parker: “Up here, I think you can get more movement on a sinking-type pitch, or a cutter or a hard slider. You may not have as much seam to work with, but there’s more ball in the sense of the density. You can kind of manipulate it better, because it’s smaller. Does that make sense? You can put that little touch on it.”

Yates: “I can’t say there’s a real difference in how my pitches move. Not that I really notice, anyway. For instance, I don’t think my slider is better in either Triple-A or in the big leagues.”

On the Carry of Batted balls

Heller: “I feel like the big-league balls fly a little bit more. I don’t know if they’re harder than the minor-league balls, or what it is. Balls that seem like they’re going to be routine flies… I even notice it in batting practice. I’ll feel like I’m camped under a fly ball, and it will go 10 feet over my head.”

Holder: “They might carry a little farther here. I’ve heard guys say they’re a little harder, but I can’t say I’ve really noticed it myself. I haven’t been here very long.”

Parker: “The ball seems to carry farther here, but that could be the wind currents and how the stadiums are. You also have factor in that the guys up here are the best of the best, and they can hit the ball a long way. Whatever it is, the ball definitely seems to fly compared to down in the minors.”

Yates: “I think the ball goes further — it flies better — in the big leagues. I’ve hung stuff in Triple-A where guys have put on a good swing and it was an out, whereas in the big leagues it was probably a home run. That could be the hitters, too — I’m not 100% sure — but it does seem like it flies more. Regardless of the reason, the balls here are definitely different.”

David Laurila grew up in Michigan's Upper Peninsula and now writes about baseball from his home in Cambridge, Mass. He authored the Prospectus Q&A series at Baseball Prospectus from December 2006-May 2011 before being claimed off waivers by FanGraphs. He can be followed on Twitter @DavidLaurilaQA.

Newest Most Voted
Inline Feedbacks
View all comments
5 years ago

Wonder if pitchfx and exit velocity comparisons for individuals could be done to prove any of this? Also, seems that some pitchers might project better or worse depending on their repitoir. As some pitches might be less or more effective in the minors. Would be interesting.