13. Joan Gregorio
Joan Gregorio has put on a bit of weight since his Augusta GreenJackets days, adding 4- to 50 pound since 2011, and that's a good thing considering the man is 6'7". His height and length definitely create a steeper angle in general, though he offsets it a bit with a sightly lower, more 3/4 arm angle. Still, 6'7" coming at you at 90-94 with good sink is nice. His slider used to be slurvy, but has now really developed into a remarkable weapon. The pitch is a straight-downer, much like vintage Tim Lincecum. The changeup looks good, too, but is not utilized as much as it could be. Like many minor league starting pitching prospects, the development and consistency of a third/fourth pitch will determine whether Gregorio reaches the bigs as a rotation or bullpen arm.
14. Steven Okert
Steven Okert will be the new Javier Lopez when Javy struts off the mound for the last time as a San Francisco Giants reliever. Swinging across his body with a jerky, low-three-quarter release, Okert is dominant against left-handers (.449 OPS in 2014, .670 in 2015) with his mid-90s fastball, sharp-biting slider, and changeup. Fellow lefty Josh Osich taught Okert his change, which he is using as a weapon against right-handers. A 2014 Fall League graduate, Okert is as close to the bigs as anyone. Expect to see him bounce between Sacramento and San Francisco until becoming a permanent staple in the big-league bullpen.
15. Jarrett Parker
Jarrett Parker will likely be the first player from this list to be removed due to exceeding rookie limits. In 2015, he became the first rookie to hit three home runs in a major league game since Andrew McCutchen did it in 2009, doing so in the infamous Zito/Hudson game in Oakland. Parker possesses plus raw power, but lacks the ability to show himself as a good contact hitter. He'll disappoint with high strikeout rates, but impress with big power, solid outfield defense, and plus speed on the base paths.