Even after throwing a 157 km/h fastball, he said, "I gave myself a score of 5." The 'No. 1 prospect' coveted by MLB, Yoon Ye-seong, wavered in his quest for higher velocity. "With the Taegeuk mark on my chest, I will go back to my own style." [Interview]

*This content was translated by AI.

Major League Baseball (MLB) teams persistently pursued Yoon, whose unofficial top speed reaches 157 km/h. Yet, when Yoon Ye-seong (17, Inchang High School) rated his own performance in his final high school season, he gave himself only a score of 5 out of 10.

Yoon will compete in the 2026 Asian Baseball Federation (BFA) U-18 Asian Championship, scheduled from the 7th to 13 in Taipei, Taiwan. Coach Jeong Yun-jin (55) of Deoksu High School is leading the Lee Kkeu-neun (CEO) team in its first attempt to reclaim the title after eight years since 2018.

Standing at 191 cm and weighing 105 kg according to the Korea Baseball Softball Association (KBSA), Yoon Ye-seong possesses a robust physique and is one of the top right-handed fireballers on the Lee Beon (CEO) team. His powerful high-velocity pitches are formidable; by his own account, his unofficial top speed reached 157 km/h, and he has recorded up to 154 km/h in official games.

Although he transferred from Gyeongdong High School to Inchang High School and only began playing regular games this year, he quickly secured the ace position. In 13 games, he posted a record of 4 wins and 2 losses with an ERA of 2.95 over 58⅓ innings, allowing 21 walks, hitting 5 batters, striking out 67 batters, and recording a WHIP (walks plus hits per inning pitched) of 1.09. Scout A from a KBO team remarked, "Yoon Ye-seong shows consistent stamina, capable of throwing pitches at speeds exceeding 150 km/h several times. While he is still raw and not fully polished, he can throw a curveball, slider, and changeup with reasonable proficiency. He is a player expected to succeed as a starting pitcher."

Another KBO team scout, B, added, "He has excellent physical attributes and flexibility. Not only does he have great velocity, but he also distinguishes his breaking balls well and possesses good feel. He has a fighter's spirit on the mound." However, Scout B noted, "Since he hasn't shown much yet, whether he can maintain consistency will be the key factor."

In fact, Yoon Ye-seong is not just a pitcher with a fast fastball. He throws five types of pitches: curveball, slider, changeup, splitter, and his signature knuckle curve. The knuckle curve, which he learned from an alumnus of his school, is his most confident breaking ball. Rather than throwing it exactly as taught, he modified it to suit himself, turning it into his primary weapon.

During the 4th Hanwha Eagles Cup High School-University All-Star Game held at Daejeon Hanwha Life Insurance Park on the 8th last year, Yoon recorded one inning with one walk and no runs allowed. However, due to appearing in three consecutive days that week, his top speed dropped to 150.8 km/h, falling significantly short of expectations.

The problem began around that time. His desire to perform even better backfired. When Yoon Ye-seong met StarNews at Ulsan Munsu Baseball Stadium recently, he said, "Starting from the Daejeon All-Star Game, I became obsessed with increasing my velocity. Afterward, I threw many pitches trying to improve my control." He reflected, "Once the game started, my velocity remained the same, but my control didn't become perfect, which made me waver."

Until the first half of the season, Yoon Ye-seong had been performing well in his own style. Even with good pitches, he wanted faster speeds and better results. The outcome, however, did not meet expectations. That is why he rated himself only a 5 out of 10 for his third-year season. Yoon stated candidly, "In the first half, I continued to do well in my own style. But in the second half, I felt that 'I've done this much and it's still not enough,' so I became even more ambitious. Trying to increase my velocity and achieve better results led to things not going as planned. As the team lost games, my score dropped significantly."

The Taegeuk mark thus became an opportunity for self-reflection. He was not even certain he would be selected. Yoon said, "I did well in the first half, but I wavered a bit in the second half and worried I might not get picked." He added with a smile, "When I finally saw the Taegeuk mark on my chest, it felt magnificent. It gave me a stronger sense of responsibility."

In this international tournament, he will face Japan for the first time, having previously experienced Taiwan as part of the Gyeong Gi-do (CEO) team in friendly matches last year. He has already studied the tendencies of Taiwanese batters. Yoon explained, "I faced the Ji Nan-hae (CEO) team before, so I know their style to some extent. They tend not to hit hard but instead use bunts or short hits to accurately advance the ball." He emphasized, "Since I have never played against Japan before, I will analyze them as much as possible before the game and pitch in my own style to ensure victory."

After representing the national team, professional baseball awaits. The first thing Yoon Ye-seong wants to improve is not velocity but control. He said, "First, I need to work on my control. Second, I haven't done weight training so far, but before joining a professional team, I think I need to build my body professionally."

At 191 cm and 105 kg, he has already reached an unofficial top speed of 157 km/h without formal weight training. The assessment that he is still raw actually fuels expectations for his future growth potential.

There is also a specific opponent he wants to face in the professional league: Hanwha Eagles' Kang Baek-ho (27). Before that, his goal is to stand atop Asia. Yoon declared confidently, "I play baseball with the thought of striking out KBO's top hitters with my pitches. Since I am representing the nation, I will win against Japan and Taiwan without exception and bring home a gold medal."

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*This content was translated by AI.