In August 2014, the year he turned 18, the Jangchung High School infielder was picked 49th overall in the Nexen Heroes’ second-stage rookie draft, and that winter he received the award given to the best high school hitter. The year he turned 19, he made his KBO League debut.
In 2018, the year he turned 22, he batted .313 in 78 games, showing promise for the first time. In 2019 he batted only .227 in 103 games and did not win a starting job, then joined Sangmu after the season.
He was discharged in July 2021 and went straight back to the first team. In 2022, he became the team’s starting third baseman, and in Game 4 of the Korean Series he had three hits and did the “Mad Dog” celebration. In 2023, he batted .263 in 104 games, and he married that December.
The breakthrough yearIn 2024, the year he turned 28, he batted .340 in 142 games, fifth in the KBO League in batting average. That November he was named to the senior national team for the first time and made captain right away, which is when he became known.
In 2025, the year he turned 29, he played all 144 games and went 20-20 with a .315 average, 26 home runs and 25 steals, and in August signed a six-year, 12 billion won non-FA contract with Kiwoom. That November he won the KBO Defensive Award, and in December his first Golden Glove, then signed a four-year deal with the San Diego Padres through posting and moved to Major League Baseball.
In January 2026, the year he turned 30, a daughter was born, but an injury kept him out of the WBC. In April he made his Major League debut as a pinch runner, and in September he was with the team as it reached the postseason in his debut season, finishing the regular season at .191.
Sung-mun Song (born Aug 29, 1996) made his KBO League debut on May 6, 2015, the year he turned 19, and became known in 2024, the year he turned 28, as captain of the Premier12 national team. On Dec 22, 2025, the year he turned 29, he signed with the San Diego Padres to move to Major League Baseball.
Ages are by calendar year (the year minus the birth year), birthdays aside.
At the 2015 second-stage rookie draft in Yeoksam-dong, Seoul, the Nexen Heroes took the Jangchung High School infielder in the fifth round, 49th overall.
Source 01 · Segye Ilbo (Korean) · From KBO “Mad Dog” to MLB · opens in a new tabSource 02 · MK Sports (Korean) · 2015 second-stage rookie draft · opens in a new tabReceived the Lee Young-min Batting Award, given to the best high school hitter.
Source 01 · Segye Ilbo (Korean) · From KBO “Mad Dog” to MLB · opens in a new tab The article says only “winter 2014,” so the month is not confirmed.Made his KBO League debut with the Nexen Heroes.
Source 26 · Wikipedia · Sung-mun Song · opens in a new tab Date from Wikipedia; not confirmed in news reports.Played 78 games, batting .313 with 7 home runs and 45 RBIs, showing promise on the first team for the first time.
Source 03 · OhmyNews (Korean) · The Heroes’ bold investment in Sung-mun Song · opens in a new tabPlayed 103 games at second and third base but batted only .227. Joined the Sangmu military team after the season.
Source 03 · OhmyNews (Korean) · The Heroes’ bold investment in Sung-mun Song · opens in a new tabDischarged from Sangmu the day before and registered with the first team right away, he started at first base, batting eighth, against the SSG Landers.
Source 04 · Sports Kyunghyang (Korean) · Discharged Sung-mun Song starts at first base · opens in a new tabPlayed 142 games, batting .247 with 13 home runs and 79 RBIs, and became the team’s starting third baseman.
Source 03 · OhmyNews (Korean) · The Heroes’ bold investment in Sung-mun Song · opens in a new tabHad three hits in Game 4 of the Korean Series against the SSG Landers, which his team won 6-3. He did a barking celebration during the game, and “Mad Dog” became his nickname.
Source 05 · Sports Chosun (Korean) · “I’ll play like a mad dog!” Korean Series Game 4 · opens in a new tabSource 01 · Segye Ilbo (Korean) · From KBO “Mad Dog” to MLB · opens in a new tabIn a season in which the team fell to last place, batted .263 with 5 home runs and 60 RBIs in 104 games.
Source 03 · OhmyNews (Korean) · The Heroes’ bold investment in Sung-mun Song · opens in a new tabHeld his wedding in Gangnam District, Seoul. Kiwoom manager Hong Won-ki later named marriage as what brought out his potential.
Source 09 · OSEN (Korean) · Married on the 17th after ten years together · opens in a new tabSource 10 · Yonhap News Agency (Korean) · The infielder who sculpts muscle, with mackerel for breakfast · opens in a new tabBatted .340 (179 hits) with 19 home runs, 104 RBIs, 88 runs and 21 steals in 142 games, fifth in the KBO League in both batting average and hits.
Source 06 · Ilgan Sports (Korean) · Named to the national team for a second straight year · opens in a new tabSource 03 · OhmyNews (Korean) · The Heroes’ bold investment in Sung-mun Song · opens in a new tab Totals compiled after the regular season; the date of the last game is not confirmed.Named to the senior national team for the first time since his 2015 debut, and made team captain, he left for the Premier12 on this day.
Signed a multi-year non-FA contract with Kiwoom for six years and a fully guaranteed 12 billion won. It was the highest ever for a non-FA position player in the KBO League.
Source 11 · Newdaily (Korean) · Kiwoom signs Sung-mun Song to a 6-year, 12 billion won non-FA deal · opens in a new tabPlayed all 144 games, batting .315 with 181 hits, 26 home runs, 90 RBIs, 103 runs and 25 steals, a 20-home-run, 20-steal season. His hits, home runs and steals were career highs for a season.
Source 14 · MHN Sports (Korean) · Golden Glove at third base, a daughter on the way · opens in a new tabSource 15 · News1 (Korean) · Golden Glove candidate interview · opens in a new tabSource 06 · Ilgan Sports (Korean) · Named to the national team for a second straight year · opens in a new tabSource 12 · Maeil Business Newspaper (Korean) · 4-year, 22.2 billion won MLB deal, 4.4 billion won posting fee · opens in a new tab Totals compiled after the regular season; the date of the last game is not confirmed.Named to the national team roster for a second straight year, after the Premier12 the year before.
Source 06 · Ilgan Sports (Korean) · Named to the national team for a second straight year · opens in a new tabChosen as the third base winner of the Defensive Award at the 2025 KBO awards.
Source 13 · MyDaily (Korean) · Defensive Award, third base · opens in a new tabReceived his first Golden Glove at third base, with 268 of 316 valid votes (84.8%). He said he had not attended the ceremony the year before because he thought Kim Do-yeong left him no chance.
Source 14 · MHN Sports (Korean) · Golden Glove at third base, a daughter on the way · opens in a new tabSource 15 · News1 (Korean) · Golden Glove candidate interview · opens in a new tabFiled for posting on Nov. 21 and signed a four-year deal with the San Diego Padres through the 2029 season. AP reported the deal at $15 million guaranteed over four years (about 22.2 billion won).
Source 16 · Seoul Shinmun (Korean) · Kiwoom’s Sung-mun Song files for MLB posting · opens in a new tabSource 17 · Newsis (Korean) · MLB San Diego officially announces Sung-mun Song · opens in a new tabSource 12 · Maeil Business Newspaper (Korean) · 4-year, 22.2 billion won MLB deal, 4.4 billion won posting fee · opens in a new tabA daughter was born. He said he asked his club’s understanding and put off his departure for the U.S. so he could see the birth before leaving.
Source 18 · Yonhap News Agency (Korean) · Expectant father leaves for the U.S. after seeing his daughter · opens in a new tabSource 19 · Star News (Korean) · News of a daughter’s birth · opens in a new tab Only a Jan. 6 article saying the birth was due in mid-January and a Feb. 1 remark by the San Diego manager that he had recently had a daughter are available, so the exact date is not confirmed.A side muscle injury from batting practice was diagnosed as a four-week recovery, ending any chance of joining the World Baseball Classic team.
Source 20 · OSEN (Korean) · Red flag before the debut, a side injury · opens in a new tabSource 21 · Ilgan Sports (Korean) · Kim Ha-seong and Sung-mun Song confirmed out of the WBC · opens in a new tabThe day after being called up from the Triple-A El Paso Chihuahuas on the expanded roster for the Mexico City Series, he made his Major League debut as a pinch runner against the Arizona Diamondbacks.
Source 22 · SPOTV News (Korean) · San Diego’s sudden call-up · opens in a new tabSource 23 · Newsis (Korean) · A grown Lee Jung-hoo and a hopeful Sung-mun Song · opens in a new tabSan Diego secured a postseason berth through the result of a road game at the Los Angeles Dodgers, so he was with the team as it reached the postseason in his Major League debut season.
Source 25 · Star News (Korean) · Postseason berth secured in his first MLB year · opens in a new tabFinished his debut season batting .191 (25 for 131) with 1 home run, 17 RBIs, 22 runs, 13 steals and a .535 OPS in 78 games.
Source 24 · Sports Chosun (Korean) · Finishes MLB debut regular season at .191 · opens in a new tabSource 23 · Newsis (Korean) · A grown Lee Jung-hoo and a hopeful Sung-mun Song · opens in a new tabEND OF SELECTED RECORDSSelected records, 2014–2026 · not a complete list of work. “Key moment” is an editorial label, not a measure of success.
What did they do, and at what age?
AgeTrail lines up the key moments of a life by age.
Debut and breakthrough are marked separately, and every record has a source.
Sports · South Korea
Aug 29, 1996 —
Ages are counted from the birth year 1996: the year of the event minus 1996, birthdays aside. “Key moment” labels and the connecting story are AgeTrail's editorial reading.
Fact-checked: 2026.09.29 · An independent archive, not affiliated with the person or their agency.