What is the difference between MLB ball and Japanese ball?

• Compare the different types of baseballs used in Japan’s NPB and America’s MLB leagues
• Understand how Mizuno baseballs are made vs Rawlings baseballs why Mizuno balls are “stickier”
• If you want to know about the differences in league rules and such, you should read How is Japanese baseball Different from American baseball post

Intro

For the 2020 Tokyo Olympics, the Japanese Olympic Baseball Commission selected SSK to provide baseballs (Mizuno provides all game balls to NPB).

During that time, several MLB pitchers raved about the baseballs, including Joe Ryan who said:

“They need this ball over America. It is amazing. It’s perfect. And the hitters love it. I love throwing with it. All the pitchers love throwing with it. SSK did an outstanding job creating this. So we need this ball. I think it would solve a lot of the current issues that with foreign substances that people like to talk about. It is, I can’t say enough, the best baseball I’ve ever touched.”

If you read my post titled Different Types of Baseballs for Different Ages, you know that MLB uses a standardized ball made by Rawlings. There are many complaints about the balls, including size inconsistency, flat seams, and slick surface (the reason why a special mud needs to be rubbed on to every single game balls). And MLB pitchers continue to try and find ways to get that extra grip to induce faster spin on a ball.

Nippon Professional Baseball (NPB) – Unified Game Ball

For the longest time, NPB did not have a standard ball which unfortunately allowed some home teams to doctor up their baseballs to gain an advantage. Since then, Mizuno has been hired to provide all games balls.

In order to perform rudimentary measurements, I had to settle with SSK “Grant Meister” high-school baseballs from Japan because I could not find those SSK game balls from the 2020 Olympics in bulk.

I also purchased few boxes of Mizuno NPB game balls to see if there were noticeable differences (Yu Darvish gifted Mizuno baseballs to his MLB friends and they were well received).

Unwrapping the Mizuno NPB baseball

Mizuno baseballs for the Nippon Professional Baseball league come individually wrapped in poly bags. Known as the “team unified game ball”, each individual balls come with a hologram sticker with a unique serial number.

Similar to Rawlings’s ROMLB baseballs, there is nothing special about the wrappings, other than a very detailed sticker. However, I was surprised to find that NPB baseballs were made in China instead of Japan.

Unwrapping the SSK “Grand Meister” baseball

Based in Kyoto, Japan, SSK Baseball produces a large number of baseball equipment, including bats, gloves, and of course baseballs.

As noted earlier, the “Grand Meister” model is used at the high-school or college level.

Unlike the wrapper for Rawlings and Mizuno baseballs, SSK balls come double-wrapped, with foil-like exterior layer followed by a shrink-wrapped inner layer.

I presume this was done to prevent moisture penetration as majority of SSK baseballs are made in Sri Lanka which has high humidity

Comparing Baseball Sizes

On a glance, it is really difficult to see the size differences between NPB Mizuno baseballs and MLB Rawlings baseballs.

But once you hold the Mizuno baseball in your hand, you can feel the smaller size right away.

The official circumference on an MLB game ball should be between 9.00 to 9.25 inches. When I measured two random boxes of Rawlings ROMLB baseballs, they averaged around 9.15 inches in circumference.

Using the same measuring method, Mizuno baseballs used in the Nippon Professional Baseball league measured 8.875 inches (or 8 7/8″) in circumference.

SSK “Grand Meister” baseballs used at the high-school and college levels measured at 9 and 9.0625 (9 1/16″) in circumference.

What was surprising was that unlike Rawlings baseballs, almost all Mizuno and SSK baseballs had the same, consistent circumference and weight measurements.

The smaller Mizuno baseballs for NPB probably has to with the fact that the majority of Japanese players are shorter in height and thus tend to have smaller hands.

Yarn Windings

All MLB baseballs are made with four different types of wool layers for windings. On the contrary, Mizuno baseballs seem to favor one type of wool layer for the entire baseball that are more tightly wound than the American counterparts.

I believe this is a key difference that leads to games with fewer home runs and lower offensive output, which in turn places a greater emphasis on pitching and strategic gameplay, thereby endowing the sport with a unique identity that distinguishes it from the American style of play.

Leather Cover

Pitchers often prefer a “stickier” leather cover on baseballs because it can significantly enhance their grip on the ball. This improved grip allows for better control over the ball’s release, enabling pitchers to more accurately execute pitches and apply the desired spin. The ability to effectively manipulate the spin on a baseball can lead to more pronounced pitch movements, making it harder for batters to hit the ball.

Japanese baseballs seem to have a larger number of “pores” which creates softer feeling to mimic stickiness. MLB baseball leather covers used to feel more slick in the past. However, a recent MLB baseball leather covers have the same features as NPB baseballs in terms of “stickiness”.

I will conduct an experiment to measure the static coefficient between two leather covers for more empirical data.

Wait, won’t having a stickier surface slow down the baseball?

While it’s true that a stickier surface could potentially increase drag due to a greater amount of friction between the ball and the air, the benefits of enhanced grip and spin control generally outweigh the drawbacks for pitchers. The increased spin can make pitches like curveballs and sliders more effective, as the greater the spin rate, the more movement the pitch will have. This makes the pitch more deceptive and challenging for batters to track and hit.

Moreover, spin efficiency and the Magnus effect, which describes the force exerted on a spinning object moving through a fluid (air, in this case), can actually help maintain the velocity of a pitch and enhance its movement, despite any potential increase in drag. The Magnus effect can cause the baseball to break or move unexpectedly due to the differential air pressure created by the ball’s rotation, adding an element of unpredictability to the pitcher’s arsenal against hitters.

Stitches

Stitching thread’s material composition, thickness, and tension in stitching all influence the ball’s aerodynamics, durability, and performance during play.

Both NPB and MLB baseballs come with 108 stiches (or 216 stitching holes).

The visual and tactile comparisons of the stitching threads between Mizuno and Rawlings baseballs were found to be imperceptible or non-existent.

Pill

NPB and MLB baseballs use a double-cushioned cork design.

Conclusion

Baseballs made for use in Japan, while bearing its roots in America, have evolved into a distinct flavor that is uniquely Japanese. Whether using Mizuno baseballs in NPB or SSK baseballs in high schools or the Olympics, Japanese baseballs come with precise and exacting standards.

But watch out, modern Rawlings baseballs for MLB have come a long way in catching up to Mizuno baseballs!