The events of 2003 prove it. The then-19-year-old hurler displayed a maturity far beyond his years that season, dominating the competition across two levels in what turned out to be his only full Minor League campaign.
Prior to 2003, Greinke's professional experience consisted of a whopping 11 2/3 innings spread over six games. Nonetheless, the Kansas City organization was confident enough in his ability to have him open the season with the Wilmington Blue Rocks of the Class A Advanced Carolina League. Ensconced at the top of the Blue Rocks rotation, Greinke quickly showed the league just why he was the sixth overall pick in the 2002 First-Year Player Draft.
"He was the best pitcher I've ever seen at that level of the Minor Leagues," recalled Billy Gardner Jr., who managed the Blue Rocks in 2003-04. "And when I say pitcher, I mean he could pitch. He wasn't just a thrower.
"At that level, you see a lot of guys with good arms but who aren't able to make the ball behave. But Zack, he was a cool customer. He was never panicked, never rattled and could command the ball and locate on a consistent basis. ... He was very deceptive and able to keep hitters from making good swings."
The numbers bear out that assessment as Greinke went 11-1 with a 1.14 ERA in 14 starts with Wilmington. He held opponents to a .178 average and walked only 13 batters over 87 innings. Perhaps most impressively, he averaged more than six innings per start, despite operating under a strict pitch count.
"He took pride in the economy of his pitches," Gardner said. "He knew what pitches worked best in a given situation and what adjustments to make. Zack could read a guy's swing and then just attack whatever weaknesses he saw.
"The one thing that concerned us was whether or not he would rot a bit, because he wasn't being challenged. But he never lost focus, and that was a testament to his makeup."
Greinke soon received a challenge in the form of a July call-up to the Wichita Wranglers of the Double-A Texas League. There, he continued to impress.
"Like Maddux, Zack had both power and finesse, and a great feel for upsetting a hitter's timing," said Keith Bodie, who managed the Wranglers from 2000-03. "He was just a baseball freak."
Nonetheless, Greinke ran into his share of trouble with the Wranglers.
"He got hit around on two occasions," recalled Bodie, now the hitting coach for the Texas League's Corpus Christi Hooks. "The first time was against Frisco and he had a tough time dealing with that. He bounced back pretty good, though, but a few starts later he faced Tulsa and just got shellacked. Now that was a pretty good ballclub -- they had [Brad] Hawpe and [Matt] Holliday. But it was still a rude awakening. He had to learn that as long as you're going out there every five days, that sort of thing is bound to happen."
Greinke rebounded nicely from the Tulsa debacle, compiling a 2.03 ERA over his next five starts. That set up his last start of the year, which offered a dramatic opportunity for redemption.
"We played a doubleheader against Tulsa on the last day of the season and if we swept them, we'd win the division," Bodie said. "I decided to throw Zack in the second game, in case we won the first, which we did. I remember handing him the ball between games and he winked at me and said, 'Skip, it's in the bag.' And he went out there and won the ballgame and we finished in first place. Zack was a big part of our success that year."
Greinke opened the 2004 season at Triple-A Omaha and after only five games received a promotion to Kansas City at the age of 20. His battles with depression and anxiety over the ensuing years have been well-documented, but as 2009 made clear, he is again operating at an elite level.
"The accolades Zack has been receiving present a new set of issues because in this game you're only as good as your next pitch," Bodie said. "But I like his chances because he's a very gifted young man."
2002: After being selected by the Royals with the sixth overall pick of the First-Year Player Draft, Greinke receives a whirlwind tour of Kansas City affiliates, pitching 11 2/3 innings over six games with three teams (Rookie-level Gulf Coast League Royals, short-season Spokane and Class A Advanced Wilmington).
2003: Greinke is utterly dominant as a member of the Wilmington Blue Rocks, going 11-1 with a 1.14 ERA in 14 starts. After a promotion to Double-A Wichita, he goes 4-3 with a 3.23 ERA in nine starts. Over 140 innings at the two levels, he walks only 18 batters while striking out 112.
2004: Greinke opens the season at Triple-A Omaha, where he compiles a 2.51 ERA over six starts. He receives a mid-May promotion to Kansas City, where he spends the remainder of the next two seasons.
2006: After a hiatus from baseball due to depression and anxiety issues, Greinke returns to Double-A Wichita and goes 8-3 with a 4.34 ERA in 18 games before returning to the Royals for good.
Benjamin Hill is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.