GOODYEAR, Ariz. -- Hunter Greene might be the most famous high school pitcher ever, with a Sports Illustrated cover proclaiming him as "The Star Baseball Needs" in the midst of his senior season in 2017. He generated 100-mph fastballs more easily than any prepster ever has, went as early in the Draft as any high school righty ever (No. 2 overall) and received the highest bonus ever given to a prep arm ($7.23 million).

Greene's first full pro season in 2018 didn't go as smoothly as he or the Reds hoped. Low Class A Midwest League hitters pounded him for a 10.06 ERA in his first seven starts at Dayton before he made progress with his secondary pitches and started pitching inside more frequently. He logged a 2.63 ERA with a 63/13 K/BB ratio in 51 1/3 innings over his next 11 starts, only to strain his right elbow in late July.

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Taking no chances, Cincinnati shut Greene down for the season. He didn't require surgery, got back on the mound in December and reported early to Reds camp to get ready for 2019. He spent his first half-dozen bullpens just throwing fastballs and changeups before adding sliders and curveballs to his mix in late February.

"It's been going really well so far," Greene said. "The progression has been great. Just confidence-wise, I feel like I'm back. I'm confident with every pitch that I throw and focusing on my bullpens and the spots I need to hit and just kind of being in sync with my body."

Greene's 2019 season will start at high Class A Daytona. He said his primary goal is to stay healthy throughout the year, and he hopes to total 120 innings and earn a promotion to Double-A Chattanooga at some point.

When MLB Pipeline sat down with Greene at Reds camp in February, he showed us the grips he uses on his four pitches -- see the video at the top of this story -- and discussed how his repertoire is developing.

Greene is best known for his fastball and reached triple digits with it 19 times while peaking at 103 mph during the SiriusXM All-Star Futures Game last July. He creates his velocity with premium athleticism and arm speed, leaving him with a stress-free delivery that bodes well for his command and should help him stay healthy.

Though he sat at 97-100 mph with his four-seamer during his first full season, he learned early on that he couldn't just throw it by professionals. His heater has late life when he keeps it down in the strike zone but can straighten out when he leaves it up. He found more success when he started pounding hitters inside and added some deception.

"It was a little tough at Dayton at first because a lot of the hitters have really comfortable at-bats," Greene said. "I wasn't moving their feet, I wasn't throwing inside too much. Once I started doing that, it changed the game.

"I was also able to hide the ball more, I was a little bit more deceptive. Earlier in the season, I was opening up a little bit and just showing the ball early. I kind of learned those things and it helped a lot."

The biggest question about Greene as an amateur was his ability to develop a quality breaking ball. He didn't demonstrate consistent feel for spinning a curveball, and most evaluators thought he would need to concentrate on his slider as a pro.

He has done exactly that, often using his slider as a putaway pitch. It usually arrives in the mid-80s and shows the makings of a plus pitch with sharp bite and good depth. His upper-70s curveball still gets too loose more often than desired and serves mainly to throw hitters' timing off because it’s the softest of his four offerings.

"My slider was my out pitch last year and it kind of always has been," Greene said. "To continue to perfect that and work on that is one of my focuses, for sure, as well as my curveball and being able to throw any pitch in any count."

Greene has less experience using his changeup because he rarely needed one as an amateur. His is still very much a work in progress yet shows promising life and separation from his fastball in the mid-80s. It did improve over the course of last season and, given his aptitude for pitching and athleticism, projects as a solid third pitch.

"I've done the four-seam changeup and stuff, but this two-seam circle change grip with the thumb under has kind of been the most successful for me," Greene said. "I didn't throw my changeup as much when I was in high school but I started throwing it a lot more my first year and then a lot more my second year when I was with Dayton, just to get guys off my fastball."