I'm separating the prospects into tiers, based on MLB availability and upside for the future. That necessarily doesn't mean one prospect is better than another, but rather which ones are more important for this year. The first tier is prospects that could outright win a starting job to open the 2016 season then progressing down to long-shot prospects. One prospect being ranked in a higher tier doesn't necessarily mean they are necessarily better, but rather ones that are more important to the team in 2016 vs. long term.
Tier 1: Top Prospects that Could Be on the 2016 Opening Day Roster
IF Brandon Drury: Drury's natural position is 3B and he's locked in a fierce battle with incumbent 3B Jake Lamb this Spring. Drury has already proven that he's ready to play in the big leagues and his 2015 numbers pay little attention to his actual ability. Drury is a plus defender at the hot corner and an above average bat. With a larger sample size and a better BABIP, Drury should put up a very strong slash-line if given the 3B job out of Spring. It should be interesting what they do if Lamb wins the 3B job and if they move him to 2B to keep the best lineup possible.
OF Socrates Brito: The Diamondbacks traded a young and talented OF, in large part due to this player's emergence as a prospect. Like Drury, Brito received a cup of coffee in 2015 but had better results. Brito has the ability to be an everyday CF at the big league level with above average or better tools across the board, although that path is blocked with an All-Star and potential MVP candidate in AJ Pollock. It remains to be seen if Brito wins a big league job at the end of camp over Yasmany Tomas in LF. If the Diamondbacks can't get Brito in the MLB lineup everyday, they should give him ABs in Reno.
C/OF Peter O'Brien: I'm not sure where he fits on the team defensively, but his power is no laughing matter. O'Brien is essentially a poor man's Mark Trumbo, a big bat with no real fit defensively. The question remains if he'll develop at a position and become a regular, because it's clear they want his bat in the lineup. He can spell Paul Goldschmidt 5-10 games at first base and fit as a RH platoon for David Peralta in the OF if you want to justify his presence on the MLB roster. Even though it's a stretch to say he'll ever be a regular catcher in the majors, he'd be more than adequate as an emergency option. O'Brien's best chance is making it as the 25th player on the roster.
Tier 2: Top Prospects that Could Contribute Significantly in 2016
RHP Braden Shipley: Shipley is the top pitching prospect in the organization now that Archie Bradley has concerns of sticking to an MLB roster. Shipley could start the year either in AA or AAA, but he should be in AAA by June if he pitches well the first month of the year if they choose to keep him in AA. Shipley has three above average pitches, but his command can lag behind his stuff. Reno's elevation and dry air should give Shipley a strong enough challenge to refine his command. If Shipley proves his worth in Reno, he should be in the Big Leagues.
SS/2B Jack Reinheimer: Reinheimer was the big ticket prospect out of the Mark Trumbo trade and he quickly proved his worth in AA Mobile in 2015. If there is an injury to either starting middle infielder, he offers minor league depth. His ceiling is somewhat limited, but his floor as a strong defender could have him challenge Nick Ahmed for the starting SS job in the future. Reinheimer will likely start 2016 in Reno, where he should be able to hit well. If his 11% walk rate sustains in AAA and the MLB level, Reinheimer could turn into a very solid infielder.
RHP Silvino Bracho: If it were up to me, Bracho would already be a lock for the 2016 bullpen and he could wind up making the roster. Bracho rolled through the minor leagues rather easily, posting insane numbers across the board. Bracho doesn't throw overpowering stuff but has a jerky delivery that hides the ball well and leads to a lot of strikeouts. When opposing hitters do make contact, Bracho is an extreme fly ball pitcher and is able to use that suppress BABIP. Relief pitchers tend to be more volatile, but Bracho's ability to generate strikeouts and limit walks can reduce the volatility.
RHP Tyler Wagner: Wagner got sent to AAA Reno already, but he could be the first player on the list if there is an injury to the current starting rotation. Wagner offers a solid sinker and slider combination with his change-up being a lagging 3rd pitch. Wagner doesn't have the upside of Bradley or Shipley, but has value as both a reliever or as a bottom of the rotation starter in the future. I don't know when he'll get an opportunity during the season, but he may only have one chance to stick in the long term.
RHP Zack Godley: Godley isn't going to have a shot to make the rotation in 2016 and may be a better fit for the bullpen. Godley has a very good cutter, but has secondary stuff that significantly lags behind. I have Godley 2nd on the list of rotation reinforcements in case of injuries and/or ineffectiveness. Godley has successful experience at the MLB level and could wind up making the team as a long reliever, although Josh Collmenter has the role on lockdown for now.
RHP Jake Barrett: Barrett has had back to back disastrous seasons in the minors, but is making a strong push for a bullpen spot. Barrett has nasty stuff, but sometimes his command can disappear on him. It's not unrealistic for Barrett to win a bullpen spot out of Spring, but I think they start him back in AAA. He would be very high on the midseason call-up priority list and I 100% guarantee he'll debut in Arizona by the end of this season.
Tier 3: Top Prospects on the Radar for 2017
2B Jamie Westbrook: Westbrook has a major challenge ahead of him in AA Mobile, which separates the cream from the crop for Diamondbacks prospects. Westbrook had back-to-back strong campaigns and a third straight strong campaign should put him on the MLB radar for 2017. Westbrook has solid speed, hit, and range at the position and has been working hard to improve his defense. Using the KATOH model that uses statistical numbers, age, and level, Westbrook ranks as the 49th best prospect (Reinheimer ranked 95th in that same model).
LHP Anthony Banda: Banda has an average fastball and breaking ball, but has a lethal change-up that already plays at the MLB level. Banda was one of the best pitchers in the California League last year and the jump to AA should tell how well he could translate to the big leagues. Banda's floor at the MLB level is as a short-inning reliever, but could develop into a bottom of the rotation guy if things go well in Mobile and Reno.
RHP Ryan Burr: The Diamondbacks drafted the Arizona State closer in the previous draft and already made it to Kane County by the end of the minor league season. It's pretty clear they will fast-track him to the majors, because his stuff and command needs very little refining in the lower levels of the minors. I would not be surprised if he starts 2016 in Visalia and ends it in Mobile. Burr has a mid to upper 90s fastball and a hammer curveball that generates a lot of strikeouts. Command will be an issue in the upper level of the minors, but Burr has the potential to be the team's closer over the long-term.
LHP Alex Young: Young is the highest picked player left in the 2015 Draft. The Diamondbacks managed Young's workload after the College World Series, but he should be ready to go for the full rigors of the 2016 season. I think he'll start 2016 in the Kane County rotation if not be their Opening Day starter and could finish the year in Visalia, depending on his performance. Young is a high floor, low ceiling type player, so he could wind up getting fast-tracked as well. His best two pitches are a late-running fastball and a solid slider. The development of a change-up could be the different between a middle of the rotation to a bottom of the rotation starter.
Tier 4: Questionable Prospects with MLB Upside
RHP Archie Bradley: Bradley went from a sure thing to an unknown within the span of two years. Injuries, bad luck, and poor command have all contributed to Bradley's fall. There's still something left to be salvaged, but his ability to stick in the majors has been handicapped by lack of command. Changing his delivery to something more repeatable hasn't helped because his poor command was an issue in camp and got him optioned to Reno. Hopefully he turns it around soon because it would be a shame to see this talent go to waste.
OF Todd Glaesmann: Glaesmann is an interesting player who most prospect guru's have likely excluded due to having aged out. Glaesmann will be 26 this year and was one of the first cuts out of Spring. He has interesting tools and could serve as a right-handed bench option later on this year. It's also very possible that he never makes the MLB team since teams have passed on him in the Rule V Draft.
OF Zach Borenstein: Borenstein had a solid Spring in 2016 and is on the radar for a potential call-up in case of an injury. His floor is a solid LH bench bat that could play both corner OF spots and potentially back up 1B. His path to the majors is blocked by superior talent and likely doesn't present a long term solution as a starter. However, he also serves as critical depth in case those players are traded or get injured.
RHP Yoan Lopez: The Diamondbacks torpedoed their 2015-16 international free agent signing pool in order to land this guy, so there are a lot of stakes with this guy. Lopez struggled transitioning to the game in the US with both blister injuries and going AWOL one week. Lopez just needs to flush 2015 as a lost season and restart 2016 in AA Mobile and hope for better luck. The Diamondbacks are hoping he can show better command and durability in 2016 as they likely have him as part of their intermediate plans.
Tier 5: Interesting Prospects in the Lower Minors
RHP Brad Keller: Keller may be the prospect with the most to gain from a successful 2017 campaign in Visalia. Keller struggled in the hitting environment in Missoula, which can be harsh to pitchers. Keller uses a sinker that generates a ton of ground balls, which could lead to a slight increase in BABIP in the Cal League where the infield plays faster in the dry environment. Keller pitches to contact and did a good job of limiting walks in the Midwest League, so his command at the next level will be critical when he starts facing advanced prospects. I have high hopes for the guy to make the rotation by the end of 2018.
OF Colin Bray: After Brito, there aren't a lot of solid CF prospects in the Diamondbacks system until you get to Bray. Bray's career has been short-circuited with injuries, but had a solid campaign in Kane County once healthy. Bray is a switch hitter with good speed and baserunning instincts, which could make him a potential leadoff hitter in the future. He'll start the season in Visalia and depending on how he does the next two years could potentially make him a replacement if AJ Pollock walks after the 2018 season.
RHP Taylor Clarke: Clarke's calling card is command and control. He has a solid fastball, change-up combination and does a good job of attacking the strike zone. Clarke isn't that far behind Young as a prospect, but I do think he's a better fit for the bullpen than rotation due to the lack of an effective breaking ball. His ability to command the strike zone proficiently should make an effective closer prospect in the near future. The Diamondbacks will try to develop him as a starter with the bullpen being a last resort, although they could accelerate his development a year as a reliever.
C Luke Lowery: Lowery had a strong summer debut in the hitter friendly Pioneer League with solid marks across the board. The only issue I have is the high strikeout total and whether his numbers are sustainable in the upper level of the minors. The entire organization is starving for catching depth and it's likely that this guy could start the 2016 season in Visalia if they like his hitting skills well enough. I'll need to find more information on how strong a catcher he is behind there, because defense at the position is understated. Fortunately, game calling is an acquired skill because his bat will be his ticket to the majors.
OF Marcus Wilson: Wilson is still a projection at this point, but already has plus speed and showed patience in his run in Missoula. The question has never been about talent, this guy has similar upside to AJ Pollock in terms of tools. It's a matter of physically and emotionally maturing in addition to gaining valuable experience. Wilson is only 19 years old, so time is definitely on his side for now. The Diamondbacks are likely going to take his development slowly, so it wouldn't surprise me if they sent him to extended Spring Training instead of Kane County.
1B/OF Austin Byler: Byler came out of Nevada as an 11th round pick, but quickly turned heads in Missoula. He produced a near Goldschmidtian line of .298/.422/.636. Byler was likely ticketed for a jump to Visalia, but has been suspended 50 games for amphetamine use. Now the question of whether his 2015 production was for real or he was juicing will be lingering after he serves the suspension. Byler has the 3-true outcomes type slugger that teams like at 1B, although his path to the position is blocked for the next 5+ years.
OF Matt Railey: Railey was an interesting prospect for the Dbacks coming out of the 3rd round of the 2014 draft, but a drug suspension and a hamstring injury have derailed his development and at 21, age is becoming a potential factor. Railey has the ability to be a MLB caliber outfielder, but he needs to start moving up the ladder fast because opportunities are starting to close. A move to full season Kane County may be too aggressive for a guy with only 122 PA in his career, though.
Other Prospects: LHP Cody Reed, RHP Wei-Chieh Huang, Jason Morozowski