Ko Won-jun

1.1. Early Life and Education

Born on June 23, 1990, in Jeju City, South Korea, Ko Won-jun attended Shin-gwang Elementary School before moving on to Jeju Jeil Middle School. He later transferred to Cheonan Buk Middle School and subsequently graduated from Bugil High School in Cheonan, Chungcheongnam-do.

1.2. Amateur Baseball Career

While attending Bugil High School, Ko Won-jun established himself as a starting pitcher for the team. In his final year, 2008, he emerged as the team's ace, achieving a record of 3 wins and 3 losses with a 2.44 ERA over 55.1 IP. Despite his performance, Bugil High School's 2008 season was not particularly notable in national tournaments, with the team being eliminated early in the knockout stages. Consequently, Ko was not widely considered a standout at the national level prior to his professional debut.

2.1. Nexen Heroes (2009-2010)

Ko Won-jun made himself eligible for the 2009 KBO Draft. Despite some scouts considering him a late-round pick, the Nexen Heroes (now Kiwoom Heroes) recognized his high strikeout numbers (9.1 strikeouts per nine innings as a starter) and selected him as the 22nd overall pick. He spent his initial professional season in the Heroes' "B" team before making his first-team debut as a relief pitcher against the Lotte Giants on April 15, 2010, where he pitched 0.2 IP of shutout baseball. His first KBO League win as a starter came on May 12 against the Kia Tigers, when he pitched six innings, surrendering only one run on eight hits. A week later, Ko pitched 7.33 IP of a no-hitter against the SK Wyverns, but he lost the no-hit bid with one out in the eighth inning after allowing a double to the 23rd batter. By May 30, he had compiled a 2-2 record with a 2.11 ERA, including an eight-inning shutout against the LG Twins where he allowed only three hits. However, he faced difficulties from June to the end of the regular season, posting a 3-5 record with a 5.03 ERA. For the entire 2010 season, Ko Won-jun finished with a 5-7 record and a 4.12 ERA across 131 IP. Although he was considered a candidate for the Rookie of the Year award, he ultimately lost out to Yang Eui-ji. Following the 2010 season, he was traded to the Lotte Giants on December 20, 2010, in a 2-for-1 deal involving relief pitcher Lee Jung-hoon and backup outfielder Park Jung-jun.

2.2. Lotte Giants (2011-2013)

Upon his transfer to the Lotte Giants, Ko Won-jun quickly made an impact. In his first year with the team in 2011, he recorded a nine-inning shutout victory against the Kia Tigers on May 28, showcasing particular strength against them. Despite early season concerns about overuse in a closer role, the emergence of Kim Sa-yul as a stable closer allowed Ko to settle into a starting pitcher role. He achieved 3 complete games, including 2 shutouts, and finished the 2011 season with a 9-7 record and 2 saves. His arrival was reportedly welcomed by then-teammate Ryan Sadowski. However, from 2012 onwards, his performance declined, which was attributed by some to overwork under then-manager Kim Si-jin and issues with pitching form correction by then-pitching coach Jung Min-tae. Following the 2013 season, Ko Won-jun decided to fulfill his mandatory military service and successfully applied to join the Sangmu Baseball Team.

2.3. Sangmu Baseball Team (2014-2015)

Ko Won-jun officially joined the Sangmu Baseball Team, the athletic unit of the Republic of Korea Armed Forces Sports Corps, in late 2013 for his mandatory military service. During his time with Sangmu, he participated in the 29th Asian Baseball Championship held in Taichung, Taiwan, in September 2015, as a member of the South Korean national team. Although he showed a struggling performance, giving up 2 runs in relief against China in the second game of the round-robin, South Korea ultimately secured the championship, marking their first Asian title in 16 years since 1999. He was discharged from Sangmu at the end of September 2015.

2.4. Return to Lotte Giants (2016)

After completing his military service, Ko Won-jun returned to the Lotte Giants. On April 6, 2016, he made his comeback start but had to leave the game after only one inning due to pain. His brief return to Lotte was short-lived.

2.5. Doosan Bears (2016-2017)

On May 31, 2016, Ko Won-jun was traded to the Doosan Bears in exchange for pitcher Noh Kyung-eun. This trade was reportedly made as a consideration for Noh Kyung-eun, who had initially declared retirement and was voluntarily released by Doosan but then expressed a desire to return to active play with another team. Despite receiving significant opportunities with the Doosan Bears, Ko struggled to perform. In 2016, he appeared in 14 games, recording 1 win and 1 loss with a 5.47 ERA. His difficulties continued into the 2017 season, where he pitched in only 5 games, registering 1 loss with a significantly high 10.61 ERA, marking his worst professional season. Following the conclusion of the 2017 season, Ko Won-jun was released by the Doosan Bears and subsequently announced his retirement from professional baseball.

4.1. Drunk Driving Incident

On December 2, 2012, in the early morning, Ko Won-jun was involved in a collision while driving his Audi vehicle, hitting an SM5 passenger car. He was subsequently booked without physical detention the following day on charges of drunk driving. The KBO League swiftly imposed disciplinary action on December 5, fining him 5.00 M KRW and mandating 56 hours of community service.

4.2. In-game Smoking Incident

While serving his mandatory military service with the Sangmu Baseball Team, Ko Won-jun was photographed smoking a cigarette during a game against the Hwaseong Heroes (now Goyang Heroes) on August 12, 2014. The image quickly circulated, leading to significant criticism from fans and the public regarding his conduct during official duty.

7.1. KBO League Career Statistics

7.2. Uniform Numbers

Throughout his professional career, Ko Won-jun wore several different uniform numbers:

• 49 (2009-2010)
• 17 (2011-2013, 2017)
• 28 (2016 - mid-season)
• 38 (mid-2016 - end of season)