The 5 youngest players to play for the KC Royals this century

Growing up, it seemed like baseball's best players rocketed through the minor leagues to The Show. Players like Andruw Jones, Álex Rodríguez, and the Upton brothers all made their MLB debuts as teenagers. That was not common for the KC Royals, so it seemed even more special. A player's MLB debut coming early in their life is not a sure-fire path to stardom, but it is still special.

This is partly due to the increased emphasis on player development in the minor leagues as well as the physical demands of playing at the major league level. However, some notable players who debuted as teenagers in the 21st century include Bryce Harper, Mike Trout, and Juan Soto. Despite the rarity of teenage debuts in modern baseball, these players have gone on to become some of the game's biggest stars.

Who are the youngest KC Royals players to appear in an MLB game?

Focusing on the youngest Royals players to make their debuts, Bobby Witt Jr. stands out as a recent exception. Most Kansas City players who have debuted in recent years have risen slowly through the minors before making it to the majors. That, like debuting young, is not a certain recipe for success, but the Royals' dismal development track in recent years has not fostered rocketing prospects.

Was this always the case? No. Let's look at the five youngest Royals players this century, with four of them coming before 2008. Which one happened most recently, in the midst of a Kansas City postseason run? Let's walk through each debut and what each player performed in their MLB career.

5. Billy Butler
Debut: May 1, 2007 (Age 21-013d)

The legend of Country Breakfast had to start somewhere. The Royals drafted Butler with the 14th overall selection in the 2004 MLB Draft. A kid out of Wolfson High in Jacksonville, Florida, Butler had massive question marks about his defense but none regarding his bat.

Legendary Royals scout Art Stewart once compared Butler's bat to Bo Jackson's before making his MLB debut. Butler left a great first impression on Royals fans with his two-hit performance against the Los Angeles Angels on May 1, 2007. Butler went on to have a great first season, with 52 RBI and a .794 OPS in his first 92 games.

Butler finally received some flowers, earning Silver Slugger and All-Star accolades in 2012. That was an elite season from the everyman Butler, who recorded career highs with 29 home runs, 107 RBI, and an astounding .882 OPS. 2014 was Butler's final year in Kansas City, coinciding with the team's best year since he made his debut.

Butler went on to play two more seasons, spent with the Oakland Athletics and the New York Yankees. It is crazy to think that Butler was 30 in his final playing year and could have had more in the tank.

Butler ended his career as a top-three batter in his draft class, making his draft slot well worth it. His career .795 OPS ranks second amongst players from that class, while many other statistics rank within their respective top 10. Butler lived up to the hype during his Royals tenure, and it all started at a very young age.

3. Zack Greinke
Debut: May 22, 2004 (Age 20-214d)

Zack Greinke is certainly the most notable player on this list, both on and off the field. The Royals drafted Greinke sixth overall in the 2002 MLB Draft, the first time they had that specific draft slot. Kansas City pushed Greinke quickly through the minor league system, picking up accolades along the way. Greinke was Kansas City's Minor League Pitcher of the Year for 2003 after spending much of the season in Double-A.

Greinke made his MLB debut early in the 2004 season, marking less than two calendar years since Kansas City drew him. He was solid enough in five innings against the Oakland Athletics, allowing two runs on five hits. Greinke went on to make 24 starts for the 2004 Royals, with an 8-11 record and 3.97 ERA. He garnered Rookie of the Year votes for his performance and finished fourth in the voting.

Greinke struggled on the mound the following year, with a 5-17 record and 5.80 ERA in 33 starts. Greinke almost left baseball after that season after battling depression and social anxiety. Those had affected Greinke for most of his life, but a poor 2005 season aggravated the issue. It is worth wondering how the pressure of being the Royals' next big thing exacerbated the situation.

Greinke did return to the MLB full-time in 2007, pitching mostly out of the bullpen. He returned to the rotation in 2008, and the rest is history. He won his first and only Cy Young Award in 2009, with a league-best 2.16 ERA and 2.33 fielding independent pitching. It seemed like the end of a movie, going from mental health battles to being the best at what Greinke does.

Following the 2010 trade that netted Kansas City several key prospects, Greinke played for five different teams from 2011 to 2021. He had plenty of success on different teams, winning six straight Gold Gloves, earning six All-Star selections, and pitching on winning teams. Unfortunately, Greinke never did win that elusive World Series ring.

Greinke returned to Kansas City in 2022, seemingly wanting to end his career where it all started. He has been a solid member of the rotation, but nowhere close to that 2009 form. Rumors are swirling that Greinke will return in 2024, but it all started for the wunderkind in a Royals uniform.

2. Adalberto Mondesí
Debut: October 30, 2015 (Age 20-095d)

Adalberto Mondesi made few fans among the Kansas City fanbase, but the hype train was running strong when he made his debut. The Royals' top prospect debuted in the World Series against the Mets, making him the first player to debut in a championship series since 1885.

The future was bright for the young Mondesi, despite spending much of the 2016 and 2017 seasons in the minors. He came to Kansas City on a more full-time basis in June 2017 and played in 75 MLB games that season. His .804 OPS and 32 stolen bases had the fan base excited for the team's future with the then-22-year-old.

Mondesi played in 102 games in 2019, which marks a career high. He led the league with 10 triples on the season but regressed slightly in many offensive categories. That was the final season where Mondesi played more than 60 games in a season, sadly. He only played in 50 games across the 2021 and 2022 seasons due to a lengthy list of injuries.

The Royals traded Mondesi to the Boston Red Sox for reliever Josh Taylor ahead of the 2023 season. While Taylor has not been a bullpen anchor, Mondesi did not play a single game for the Red Sox last year. He is currently a free agent at 28 years old. When he made his debut, Mondesi's future was bright. Now, in his prime playing years, fans have to wonder if we will see Mondesi on the field again.

1. Andrés Blanco
Debut: April 17, 2004 (Age 20-006d)

Andrés Blanco was supposed to be the future for the Royals I mean, he was in the 2004 Futures Game after all. The expectations that come from playing alongside players like Justin Morneau and Robinson Cano were high, But Blanco never quite lived up to them. Still, the Venezuelan is the Royals' youngest player this century.

Blanco debuted against the Minnesota Twins on April 17, 2004, going hitless in three at-bats. He did not stick with the MLB club for long, playing eight more games after his debut before the Royals demoted him. The same situation happened in August, with Blanco playing in go-go games between Aug. 10 and Aug. 22. He had great numbers in those 19 games, though, with a .379 on-base percentage and four extra-base hits.

Despite promising numbers, Blanco did not see much more action in the next two seasons. That decision seems like the correct one. Blanco played in 59 games across the 2005 and 2006 seasons. He only had a .534 OPS, and the on-base percentage dropped to .257. A labrum tear in September ended his season early and contributed to his not playing MLB ball in 2007.

Blanco went on to have a long playing career with the Chicago Cubs, Texas Rangers, and Philadelphia Phillies. He last appeared on Sept. 17, 2017 for the Phillies, marking the end of his career. His career .688 OPS and 1.6 bWAR are solid for a transient utilityman, but the Royals were wise to not retain Blanco long-term. He still took his first MLB steps with the boys in blue at a very young age.