Here is what Sickels has to say about the Arizona prospects:
13) Arizona Diamondbacks (9): Strengths: good group of pitching prospects, with Tyler Skaggs, Archie Bradley, Andrew Chafin, David Holmberg a sound group with several of C+/B- beyond them. Weaknesses: Impact hitting, though Adam Eaton and Matt Davidson can be regulars and Stryker Trahan must be watched closely. Overall a solid system.
I would recommend that, for context, you read the full rankings, covering all 30 teams, with strengths and weaknesses for each franchise. I'm sure John B will be along with a slightly more informed opinion, but that ranking sounds about accurate. Obviously, the departure of Trevor Bauer has had some impact - though, I note, it doesn't exactly appear to have helped the Cleveland Indians very much, as they are ranked all the way down at #24. But, if our pitching is somewhat depleted, the system is certainly a lot stronger up the middle than it was a year ago.
Looking round at our division, it was no surprise to see the Padres still the highest-ranked in the NL West, up in sixth spot. They are the only one of our rivals also to be in the upper half, though the other teams don't miss out by much. The Rockies, Giants and Dodgers are all bunched together with Colorado leading the the way in sixteenth, followed right behind by San Francisco, with Los Angeles a couple of spots further back. Overall, Sickels reckons the best system belongs to the St. Louis Cardinals, while the worst one is owned by the Detroit Tigers.
There's agreement on the top spot from Baseball America's Jim Callis, who issued his top 10 farm systems earlier in the month. He actually ranked the Diamondbacks higher, at #9, and that was before the Upton trade which added a couple of new names to our system. Of course, all these things are, as Sickels points out in his introduction, highly subjective, and of dubious correlation to future major-league success. But it's still interesting to see where opinion ranks the Diamondbacks, in comparison to other teams.