Prospect Smackdown: Simon Castro vs. Casey Kelly of the San Diego Padres
Prospect Smackdown: Simon Castro vs. Casey Kelly
The two best pitching prospects in the San Diego Padres system are right-handers Simon Castro and Casey Kelly. Per reader request, here is a Prospect Smackdown comparing the two.
Background and Intangibles
Castro: Simon Castro was signed by the Padres as a free agent from the Dominican Republic in 2006. He was considered raw when signed, but the Padres liked his arm strength and projectability. After a pro poor debut in the Arizona Rookie League in '07, he was one of the better pitchers in the Northwest League in 2008, then broke out with a strong campaign in the Midwest League in '09. He jumped to the Texas League in 2010, continuing to pitch well and finishing the season with two starts in Triple-A. Although on the 40-man roster, he's expected to return to Triple-A for 2011 with a chance for a second-half promotion to the majors. Although scouting reports focus on his stuff, Castro is said to have good makeup.
Kelly: Casey Kelly was drafted by the Boston Red Sox in the first round in 2008, out of high school in Sarasota, Florida. A two-way player, it cost $3 million to sign him, and the Red Sox let him play shortstop (his preferred position) in 2009, splitting the season between mound work and the infield. He showed a good glove but couldn't hit, so he moved back to the mound full-time last year. Sent to Double-A at age 20, he did not pitch well on a statistical basis, but scouts remained impressed with his talent. He comes from a baseball family (his father Pat played in the majors) and shows good makeup and mound presence. He was traded to the Padres in the Adrian Gonzalez deal. He is expected to begin 2011 in Double-A, with Triple-A possible later in the year.
Advantage: Kelly had a higher-profile as an amateur. Both of them have shown good "intangibles," though most scouts would probably rank Kelly just a bit higher. That doesn't mean there is anything wrong with Castro, but it shows how well-regarded Kelly is.
Physicality, Health, and Tools
Castro: Castro is a 6-5, 210 pound right-handed hitter and thrower, born April 9, 1988. His key pitch is a 90-93 MPH fastball that tops out at 96, with movement. His slider gave trouble early in his career but is a much better pitch now. It can still be inconsistent but is a plus pitch when it's working. His changeup is gradually improving but still needs some polish. Castro shows good control for a young power pitcher, though his command within the strike zone isn't always terrific. His stuff is good enough that this hasn't been a problem the last two seasons. A good athlete, his mechanics are somewhat unconventional with a long arm stroke and some whippy action, but it adds deception. So far he has had no major health concerns, although some scouts worry that his delivery strains the shoulder.
Kelly: Kelly is a 6-3, 210 pound right-handed hitter and thrower, born October 4th, 1989. He can hit 95-96 on his best days, but works more commonly in the 88-93 range. Although he throws strikes with it, his command within the strike zone still needs polish, making the fastball more hittable than it should be. His changeup is very good and should get better. His main breaking ball is an erratic curve, which ranges from a plus pitch to a below average pitch, depending on what day you see him. He is an excellent athlete, as befits a former shortstop. He repeats his delivery well and it is relatively smooth although not completely textbook. So far he's had no major league concerns, although his regular season ended early due to a strained lateral muscle.
Advantage: Castro has a better fastball and a more consistent breaking ball. Kelly has a better changeup. Both have solid control, though Castro's is better statistically at this point, and both still have occasional troubles with location. Castro is a good athlete but Kelly is an excellent one. Both of them have good health records. Kelly's mechanics are more conventional. Very tough call here. I think Castro has a slightly better arm in terms of pure strength and more consistent velocity, though Kelly is hardly a slouch. This really looks "even but different" to me, if that makes any sense.
Current Performance
Castro: Castro went 7-6, 2.92 with a 107/36 K/BB in 130 innings last year for Double-A San Antonio, with 107 hits allowed and a 3.32 FIP, 1.13 GO/AO. He made two Triple-A starts, giving up 16 hits in 10 innings with a 6/6 K/BB.
Kelly: Kelly went 3-5, 5.31 with a 81/35 K/BB in 95 innings for Double-A Portland, with 118 hits allowed and a 4.03 FIP. He posted a 1.30 GO/AO. Note that his FIP was much better than his ERA, but still, it wasn't a great year.
Advantage: Although we can cut Kelly some slack due to his age and relative lack of experience, Castro is a more consistently effective performer right now.
Projection
Castro: Although there has been talk of Castro becoming a reliever in the past, he made enough progress last year to project as a number three starter, possibly a number two if he maximizes the changeup and develops even sharper command.
Kelly: Kelly looks like a strike-throwing number three type to me, although many scouts believe that if the curveball gets more consistent, he can be a number two.
Advantage: They could take different paths to get there, but both of them could be/should be number three starters and perhaps number twos if all goes well. I don't think either of them projects as a classic ace rotation anchor, but they don't have to be that to be valuable.
Summary
I give Kelly the edge on background/intangibles, "different but even" on physicality, Castro an edge in current performance, and "different but even" in projection. Both got Grade B ratings from me in the 2011 Baseball Prospect Book. A lot of scouts would put Kelly ahead because he's a better athlete, but I rated Castro at 35 and Kelly at 40 on my Top 50 pitchers list, giving Castro the slight edge because he is closer to the majors.
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Two good prospects
Good article & I concur with the bulk of it. I think you’re right - both have the ability to settle in as very good #3/low end #2 type starters, but I am a big believer in Casey Kelly’s skillset & think that he has the ability to even be a bit more. He’s not an uber ace Zack Greinke type, but I think he could possibly anchor a rotation - especially potentially in a place like Petco Park.
I just can’t board the train of thought that claims that Kyle Drabek is a superior prospect to Kelly. To me, if I were ‘bizarro Alex Anthopolous’ & ‘bizarro Jed Hoyer’ offered me Kelly SU for Drabek, then I would do it in a heartbeat even though they’re similar in some ways & Drabek is closer to MLB. To me, Kelly has better mechanics, a better frame (both are athletic, but give me Kelly), & better potential to develop an acceptable third pitch. While Kelly’s change is a fantastic offering, it probably isn’t on the level of Drabek’s breaking ball & likely never will be. Having said that, I believe in the potential of Kelly’s curveball (at least as a ‘show me’ pitch) at least as much as Drabek’s changeup if not more. This will be telling with both young pitchers. However, given Drabek’s middling peripherals in what was essentially a second go-round in AA in ‘11, I prefer Kelly & still maintain that he has superior upside. 2010 was his first campaign as a full time starting pitcher & he was young for the level to begin with - I wouldn’t jump ship on this kid. I expect him to shine in 2011 & I kind of wonder if SD will even bother exposing Kelly to the hitter friendly PCL considering his youth & relative lack of experience as a full time starter (at least this year).
by Matt0330 on Mar 3, 2026 10:30 AM EST reply actions
Where did Drabek come into the discussion?
So confused…
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by JD Sussman on Mar 3, 2026 11:36 AM EST up reply actions
Sorry for the non sequitur
Ha, yeah that got out of hand quickly. I was merely attempting to show some support for the idea of Kelly being a superior prospect (to me) than a somewhat similar (yet older) prospect in Drabek that many services have ranked higher heading into 2011. I’m an ardent Toronto fan too for whatever that’s worth so it’s not as if I’m blinded by fan bias.
In terms of the Kelly-Castro H2H matchup, I think it can be ascertained that I would side with Kelly.
by Matt0330 on Mar 3, 2026 11:51 AM EST reply actions
I totally agree on Castro.
Relatively, I am not a fan. John’s report is the first that I can recalled off the top of my head that graded his slider so highly. When I spoke to MrKupe privately a few months ago, I recalled he did not have glowing reports of the pitch when he saw him in person. Normally, I would actually rank these guys offerings as Kelly-FB, Kelly-CU, Casto-FB, Kelly-CB, -Castro-SL. As, I believe Kelly’s movement and control make his fastball more of a weapon than Castro’s which has more velo.
I disagree on Drabek, but I don’t have time to elaborate. You’ll just have to see my comments on our top 100 or later today.
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by JD Sussman on Mar 3, 2026 12:04 PM EST up reply actions
castro
Castro’s slider is erratic but I have seen it look Plus.
Kelly’s curveball is erratic too.
I admit I like Castro more than some people do.
by John Sickels on Mar 3, 2026 12:28 PM EST up reply actions
Thanks, John
Appreciate the insight.
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by JD Sussman on Mar 3, 2026 1:10 PM EST up reply actions
Castro Fastball
Unless you really think Kelly’s FB and change are plus pitches, I can’t agree with that. Castro’s fastball has both speed and movement that are very good. (I haven’t seen Kelly’s in person, so I won’t say Castro’s is better than his in those regards, but if Kelly’s is significantly better, I’m a VERY happy Padre fan!)
by realitypolice on Mar 3, 2026 2:40 PM EST up reply actions
Thanks for posting this John
I enjoyed reading it. Question- is the Padres 2014 rotation:
Latos, Richard, Castro, Kelly, Luebke?
by noelman31 on Mar 3, 2026 3:00 PM EST reply actions
Was just about to say those 5 make for a fine rotation
even if no clear cut #2 after Latos….now if only we can somehow replace Adrian’s power.
"I didn't really say everything I said."-Yogi ism
by chewbalka on Mar 3, 2026 3:04 PM EST up reply actions
Oramas is going to start the year in AA with Kelley and has to at least be considered for the rotation as well.
by AirmanSD on Mar 3, 2026 9:11 PM EST up reply actions
If you are going to include Oramas
Don’t leave out Lollis!!
by slickwdb on Mar 4, 2026 8:10 PM EST up reply actions
The reason I left off Lollis is cause he is going to start the year in High A
I know that is only one step below double A but I was limiting to to arms that are going to be in the high minors (AA and above)
by AirmanSD on Mar 5, 2026 2:11 AM EST up reply actions

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