Arizona Diamondbacks 2019 Top 30 MLB Prospects Midseason Update

Image credit: Alek Thomas (Photo by Paul Gierhart)

UPDATE: The D-backs list has been updated to take into account the Zack Greinke and Jazz Chisholm trades.

The D-backs still have the feel of a farm system on the rise, but some of their more advanced prospects hit speed bumps in the first half of 2019 and many of their prospects with the highest upsides reside at the lower levels, making them riskier and likely several years away.

The front office also remains in a sort of needle-threading mode in which it attempts to simultaneously win at the major league level while also rebuilding the system below. That’s not easy to do, and it will be further complicated if the club decides to become a buyer at this year’s trade deadline.

Overall, Arizona’s farm system is still more about potential than reality. They have a handful of intriguing teenage prospects in the lower levels and added a slew of talented, yet unproven players in the draft, in which they had seven of the first 75 picks.

1. Zac Gallen, RHP

The biggest riser in the Marlins’ system through the first half of 2019, Gallen dominated at Triple-A New Orleans before making his major league debut on June 20. The righthander has advanced command of his entire arsenal, including a low- to mid-90s fastball and a heavily used, mid-80s cutter that he can manipulate to feature slider-like break. Miami traded Gallen to the Diamondbacks hours before the July 31st trade deadline, receiving Jazz Chisholm, Arizona’s No. 3 prospect, in return. 

2. Alek Thomas, OF

Thomas has shown an innate ability to find the barrel and drive the ball with power. He’s drawn comparisons to current Nationals outfielder Adam Eaton as he tears about low Class A pitching.

3. Daulton Varsho, C

Varsho has had a solid if unspectacular year in Double-A. He’s hit well, but he hasn’t had a prolonged hot streak.

4. Kristian Robinson, OF

Perhaps no player in the system has a better combination of athleticism, tools and frame. Robinson is off to a hot start at the short-season level, hitting for average and power while showing a patient approach.

5. Corbin Martin, RHP

Martin struggled in his first five starts with Houston, but other than acclimating to a new level, he didn’t show any insurmountable hurdles. Unfortunately, his recovery from Tommy John surgery means he likely won’t be back in for good until 2021, where he’ll presumably return in a D-backs uniform after they acquired him in the Zack Greinke July 31st blockbuster. 

6.  J.B. Bukauskas, RHP

Coming into the season, it was logical to think that Forrest Whitley, Martin or Bukauskas would have stepped into the Astros’ rotation by now. Whitley has gotten rocked in Triple-A, Martin received an MLB callup but struggled before going down with an elbow injury and Bukauskas has been wild and hittable in Double-A. Now, two of those three, Martin and Bukauskas, are gone (dealt to Arizona in the Greinke deal) and Whitley is slowly building his innings back in the lower levels of the minors. Bukauskas still throws hard, has an excellent slider and his changeup has improved, but it won’t matter until he can refine his fastball command.

7. Corbin Carroll, OF

The D-backs see in Carroll a player similar to Thomas—an up-the-middle defender who might be undersized but has enough strength in his swing to be an impact bat.

8. Jon Duplantier, RHP

Reports on Duplantier’s stuff haven’t been as glowing as in previous seasons, and he has added another line to his lengthy injury history as he deals with shoulder inflammation.

9. Levi Kelly, RHP

Kelly has shown maturity, poise and a major league-quality fastball-slider combo while pitching in the low Class A Midwest League this season. He has a chance to grow into a mid-rotation starter if his fastball command continues to improve.

10. Brennan Malone, RHP

A first-round pick out of high school in 2019, Malone is righthander with athleticism, a strong build and present stuff that includes a mid-90s fastball and a power slider. 

11. Seth Beer, 1B

Beer is a all-bat, no-glove first baseman/DH, and the Astros’ defensive expectations at first base—former shortstop Yuliesky Gurriel currently plays there—would have been a tough ask for Beer. He’s answered the questions about whether he can hit with a wood bat, however, and his combination of patience and power is exceptional. Now, he’ll prove himself in the D-backs organization after he was one of four prospects included in the Greinke haul.

12. Geraldo Perdomo, SS 

Perdomo has as many walks as strikeouts in his first taste of full-season ball, and the organization is hopeful that as he gets stronger he’ll be able to blend in the ability to drive the ball with more authority.

13. Taylor Widener, RHP

Widener endured a miserable first two months with Triple-A Reno, but he has pitched better since an adjustment got him back on track mechanically.

14. Luis Frias, RHP

15. Blaze Alexander, SS

16. Drey Jameson, RHP

17. Matt Tabor, RHP

18. Blake Walston, LHP

19. Josh Green, RHP 

20. Josh Rojas, 2B

21. Taylor Clarke, RHP

22. Tommy Henry, LHP

23. Dominic Fletcher, OF

24. Wilderd Patino, OF

25. Liover Peguero, SS

26. Andy Young, 2B

27. Buddy Kennedy, 3B

28. Kevin Cron, 1B

29. Eduardo Diaz, OF

30. Riley Smith, RHP


In a system that’s light on potential starters with dominant stuff, RHP Luis Frias has been holding mid-90s velocity into the fifth inning with a plus curveball.

OF Wilderd Patino has a raw approach but is built like a free safety and has the chance to hit, hit for power and stick in center field. 

He’s in the hitter-friendly Pioneer League, but SS Liover Peguero is crushing balls and holding his own at shortstop.

RHP Riley Smith doesn’t miss a ton of bats, but his fastball can touch the mid-90s, he has two secondary pitches (changeup and slider) that he trusts and he knows how to change speeds.

2B Josh Rojas was rising in the Astros system before being dealt. He has played every position other than center field and catcher this year, but it’s his ability to hit consistently that has him forcing his way to a future major league role. He fits best as a utilityman, and if future roster rules reopen the door for bench bats, he’d be useful.

RHP Zac Gallen had risen in the Marlins system to the point that he won’t be on this list much longer, as he should exhaust prospect eligibility later this summer as a newfound mainstay in the D-backs’ rotation. Commonly seen as a potential No. 4 or No. 5 starter before the season began, Gallen’s improved command and sharpened offspeed offerings have pushed his ceiling to that of a potential No. 3 starter at the major league level.


1B Pavin Smith has tried tinkering with his swing and being more aggressive in his approach, but the production hasn’t been there for the second year in a row.

C/1B Andy Yerzy got off to a horrible start in the Midwest League and for the fourth season in a row finds himself back at a short-season affiliate.

OF Jake McCarthy has been trying to retool his swing over the past year but hasn’t been able to put it all together yet at high Class A Visalia.

RHP J.B. Bukauskas 2019 numbers were almost as bad as former organization-mate Forrest Whitley’s. He’s shown some positive signs recently, and he did make the Futures Game roster, but Bukauskas’ fringe-average control and command have gotten worse this year, which means he’s left his fastball over the heart of the plate too often. With fewer advantageous counts, he’s had less chance to use his plus slider.


RHP Kevin Ginkel missed six weeks with elbow inflammation but returned to the mound for Double-A Jackson earlier this month.

RHP Harrison Francis dealt with a UCL sprain that pushed back his season debut, but he returned to the mound in the Rookie-level Arizona League on July 8.

RHP Emilio Vargas, who has been bothered by a shoulder impingement this year, hasn’t been as sharp or consistent with his stuff as he was last season.

RHP Corbin Martin will miss the rest of the season and much of next year as he recovers from Tommy John surgery.


RHP Yoan Lopez has picked up where he left off last September, quickly emerging as perhaps the D-backs’ most reliable reliever.

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