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.