The first thing to remember about Ryan Castellani is that he's younger than you think he is. As in, he's only 19 (will turn 20 in April), just four months older than Colorado's 2015 top pick, Brendan Rodgers. Despite his youth, the 6'3 right-hander already has a successful year of full-season ball under his belt. That's a hugely positive outcome for Castellani, who signed out of an Arizona high school for $1.1 million (slightly under slot) after the Rockies picked him in the second round of the 2014 draft.
Here's a selection of what prospect guru David Hood said about Castellani when the Rockies drafted him:
Castellani's strengths are closely tied in to the Rockies' pitching philosophy preached over Spring Training, that being the use of a heavy two-seam fastball down in the zone to limit hard contact. ... The knock you read on Castellani is in his secondary pitches, and in the videos available, it's hard to see much of either his curve or his change. ... Because he lacks the power of pitchers going around him, Castellani may require a bit more time in the lower levels before starting his climb, and he probably doesn't project more than a No. 3 or 4 at this point.
Castellani's delivery has been compared to Eddie Butler's; while Castellani's secondary stuff might not be there now, he seemed like a scheme pick for Colorado's pitching philosophy. After the draft, the Rockies showed a lot of faith in Castellani when they skipped the high school pick over the rookie league Grand Junction Rockies and into Short Season-A ball with the Tri-City Dust Devils.
In 37 innings over 10 starts in the Northwest League, Castellani held his own with a 3.65 ERA, 1.19 WHIP, 4.23 FIP, and 6.1 K/9. In a great pitching environment like Tri-City, those aren't spectacular numbers (especially the K rate), but in the context it was more than acceptable for a high school draftee debuting in a league filled with hitters that were more than three years older on average.
In 2015, Castellani made his full-season debut with Low-A Asheville with a pretty strict innings/pitch limit in each one of his starts. In 113⅓ innings over 27 starts with the Tourists (so, just over four innings per start, continuing the trend established in 2014) -- against hitters three years older than him (he was among the youngest players in the South Atlantic League) -- Castellani had a 4.45 ERA with a 1.44 WHIP, 3.27 FIP (a very positive sign), and 7.5 K/9. Again, those aren't numbers that will blow you away (especially the relatively low strikeout numbers, the attribute that keeps him from ranking higher), but considering the context they're still pretty darn impressive.
In its year-end evaluation of Colorado's minor league system, MLB.com rated Castellani as the 17th-best prospect in the system:
The former Arizona high school standout has an excellent combination of size, stuff and feel for pitching. His fastball sits in the low 90s, and there's room for more as he adds strength to his 6-foot-4 frame. His breaking ball gets caught in between, more of a slurve right now, but he's worked at tightening it up. He has a good feel for his changeup as well. He can throw all three for strikes, and there's sink on his fastball, generating groundball outs. He throws a lot of strikes but still needs to refine his overall command, something there is confidence he'll develop over time.
As Castellani builds innings, he should be able to fine-tune his stuff and his command. If that happens, he should be able to reach his ceiling of a solid middle-of-the-rotation big league starter.
The combination of draft pedigree, advanced placement, and results to date led me to place Castellani 17th on my list. I'm excited to see what he can do at a higher level next year (presumably at Modesto), perhaps with fewer restrictions on his workload. If he continues on this trajectory (which is assuming a lot, admittedly), Castellani could be in line for a major league debut before his 23rd birthday.