“It did not come easy. But it’s here all the same. Let the party begin in Taiwan – Chinese Taipei is back to the World Baseball Classic!” said Tyler Muan, the broadcaster for the World Baseball Classic Qualifier, after Team Taiwan, aka Chinese Taipei, secured last out in a win-or-go-home game and advanced to the WBC 2026.
That quote summarized my feelings watching the entire series.
Since only one professional ballpark in Taiwan provides advanced data like spin rates, I want to take this opportunity to examine the WBC data of Team Taiwan’s players and see if I can find anything interesting. To avoid making this article a master’s thesis, I will focus only on pitchers in this post and leave batters to the next one.
Jyun-Yue Tseng
Tseng is the closer for the Fubon Guardians of CPBL, the professional baseball league in Taiwan, and ranked 11th on the international board for pitchers on Fangraph. He was picked in the 7th round of the 2020 mid-season draft and won the Rookie of the Year award in 2021. He also keeps the record for the fastest ball in CPBL at 99 mph (158 kmh).
Given that Tseng also participated in the 2023 WBC, I will compare his data from these two series in this section.
Please note that Tseng pitched one full inning (the 9th against Team Spain) and only threw four-seam fastballs in the 2025 WBCQ. In 2023 WBC, he pitched two innings—one in the 6th against Team Panama and another in the 7th against Team Cuba – with four-seam fastballs, sinkers, and sliders.
Since Tseng only threw four-seam fastballs in 2025, let’s compare how effective they were in 2025 vs. 2023.
- Higher velocity – one reaches 97.3 mph.
- Higher and more consistent spin rate, which results in lower drop, i.e., the ball appears to rise.
For the chart nerds reading, below are the quartile charts for every metric of Tseng’s four-seam fastballs in those games.
Unfortunately, I can’t find any data from WBC, such as active spin, arm angle, or extension, to support this improvement.
Jo-Hsi Hsu
Hsu, nicknamed “the son of the dragon,” is the ace of the Wei Chuan Dragons in CPBL. He’s ranked 9th on the international board for pitchers on Fangraph and will be eligible to be posted at the end of 2025.
Hsu gave up one run and struck out five batters in 3.1 innings against Team Spain. The following are his stats in that game.
Among all his stats, the most prominent one should be the whiff rates – a whopping 48%, meaning that nearly half of the swings didn’t even touch the ball. Hsu’s changeups contribute the most to that metric.
But what makes Hsu’s changeups so hard to hit?
If we compare all of the pitchers that throw changeups in 2024 in the MLB, we can find that:
- Within the tight velocity range (83-85 mph)
- 21 MLB pitchers throw changeups at similar velocities
- The lowest spin rate is 1,409 RPM (Nestor Cortes Jr.)
- The average spin rate is 1,803 RPM, and Hsu’s is only 50% of that.
- Within a wider velocity range (82-86 mph)
- 40 MLB pitchers throw changeups in this range
- The lowest spin rate is still 1,323 RPM (Jose Quintana)
- Hsu’s changeup would be at the 0th percentile – no MLB pitcher with similar velocity has a spin rate this low
To put things into perspective – here is a scatter plot in which the x-axis shows the average velocity of an MLB pitcher’s changeup, and the y-axis shows the average spin rate of his changeup. You can see Hsu sits alone close to the x-axis with no adjacent player.
No, the WBC Qualifier records data using Statscast, the same system MLB uses. MLB also sets up the venue, so it’s unlikely that this anomaly derives from measurement errors.
This unusually low spin rate means Hsu’s changeup experiences much less ‘lift’ than normal, causing it to drop unexpectedly – more like a splitter than a typical changeup. At the same time, both his fastball (8.7 inches) and changeup (12.1 inches) move in the same direction horizontally, which maintains the pitch deception longer. To experience that yourself, below is Hsu’s balls’ trajectory from 3rd base view (red: four-seam fastball, green: changeup):
As you can see, fastballs and changeups initially look the same. However, changeups start to drop faster around the middle of their fly path, making it extremely difficult for hitters to square up, even when actively looking for them.
One last piece of evidence to back up its effectiveness is that Hsu’s changeup averages 84.0 mph compared to his fastball at 95.4 mph. This 11.4 mph (≈11%) difference is exceptional as the most effective changeups are usually 5~12% slower than fastballs.
Yu-Hung Chen
Chen is a submariner for TSG Hawaks in the CPBL. His ERA+ in 2024 is below average in the league, and I believe he was picked due to his unusual delivery mechanics.
Chen started against Team Spain in Team Taiwan’s first game in this series and was a setup pitcher against Team Nicaragua. He gave away two runs in one inning in the first game but none in the second.
This section will analyze whether significant statistical differences explain these dramatically different results.
First, we can see more strikes in the latter game—38% vs. 76%, to be exact. This throwing-in-strike-zone-and-letting-batters-hit style aligns more with how Chen dealt with batters in the regular season. Additionally, Chen had much more command in the second game, judging by where the pitches landed.
Moreover, in the second game:
- His two pitches had a higher velocity.
- His two pitches had a much difference in horizontal breaks.
The combination of these two might explain the 20% whiffs in the second game vs. 0% in the first.
However, one thing worth pointing out is that Chen’s release points between pitch types in the second game were slightly different. I believe the Nicaraguan team didn’t notice this during the game, but if Chen had pitched for more innings, they would likely have noticed and punished him.
Conclusion
After analyzing the WBC Qualifier data, I focused on these three Taiwanese pitchers whose performances revealed the most compelling stories. I removed sections about other pitchers either because the findings weren’t particularly distinctive or because the available data didn’t allow for meaningful analysis.
What stands out from this deep dive is how advanced metrics can reveal hidden strengths that might go unnoticed in traditional statistics. Jyun-Yue Tseng’s improved fastball characteristics from 2023 to 2025 show his development as an elite closer. Jo-Hsi Hsu’s changeup represents something truly unique—a pitch with characteristics that don’t exist anywhere in MLB. Yu-Hung Chen’s case demonstrates how even pitchers with below-average regular season stats can find situational success when they adapt their approach.
In my next article, I’ll focus on Team Taiwan’s batters, examining their performance through a similar analytical lens. I aim to explore the likes of exit velocities, launch angles, and other metrics that reveal which hitters stood out during the WBC Qualifier and why. Some players to be studied in mind are Yu Chang, Nien-Ting Wu, Po-Hsuan Wang, and 2024 Premier 12 MVP Chieh-Hsien Chen.
Stay tuned!
