Prospects the Diamondbacks Must Evaluate Before 2026

With 51 games left in a lost 2025 season, the Arizona Diamondbacks need to shift their focus to shaping the 2026 roster. That means giving their top upper-level prospects a real opportunity to prove they belong in the big leagues.

This will be a painful process for fans in the short term, as the team tries to find its identity with a new core of players. That process will continue into 2026, while the team awaits their top arms (Corbin Burnes, Justin Martinez, A.J. Puk) to finish their rehab from elbow surgery. By the end of that season, the organization needs to know who will help them win and what they need to add to make themselves a contender again.

Mike Hazen must handle this evaluation period with care, with his legacy as the D-backs’ GM on the line. A collapse in 2026 will cement his tenure as a GM who caught lightning in a bottle but never could recreate that success. However, if this short rebuild is done the right way, he’ll achieve that sustained success he’s been seeking.

To make the most of that window, the team needs to start promoting their top prospects in Triple-A to the major leagues now. These prospects, all currently on Arizona’s 40-man roster, fit that criteria.

Can Jordan Lawlar Handle the Hot Corner?

Six months ago, the D-backs’ top prospect was the shortstop of the future. With Geraldo Perdomo extended through 2029, there was no clear position to move him to in 2025. However, a new opportunity has emerged following the team’s sell-off at the trade deadline. One of those moves involved returning Eugenio Suárez back to the Seattle Mariners, giving Lawlar a potential runway to take over at third base for the next 12 months.

Lawlar doesn’t necessarily fit the stereotypical mold for a third baseman. His best defensive traits are excellent body control, good range, good hands and actions, and the ability to throw off-platform. The only thing that’s missing is a strong arm. With no clear long-term fit at the position and Lawlar having more than enough defensive tools to handle the position on 90% of the plays, it’s fine to keep him there until a better defensive fit comes along. He’s still controllable through 2031 if he never plays another game in the minors.

With the full runway of playing time, his bat needs to start showing up. One thing is clear about Lawlar’s pitch selection profile. He murders fastballs, especially four-seamers above the thighs and in the middle of the plate to the inner third. He is very good at turning on those pitches and barreling them to his pull field.

That approach will lead to damage, but it carries one fatal flaw. Lawlar is especially vulnerable to soft stuff, especially fading down and/or away from his bat path. He has struggled to identify and produce competitive swings against spin, something that was recently exploited in a short stint in the major leagues earlier this season. This season, he’s seen breaking pitches on 40 of 86 total pitches (46.5%) and has a whiff rate of 52.2%.

Lawlar simply is going to have to pass his trial by fire. Teams know of his vulnerability to spin, but the only way to improve his approach is to see more of it so he can recognize and counter it. That may mean he carries a strikeout rate well north of 30% for the rest of the season, but the hope is he can check off the pitch and force more fastball counts with more exposure to major league pitching.

Of course, Lawlar also needs to stay healthy to get those opportunities as well. He’s only been relatively healthy in two of the five seasons he’s spent in the organization (2022 and 2023). He’s currently on the 7-day IL in the minor leagues for a hamstring injury, but is rehabbing in continuation camp and should be back in Reno shortly.

Can Tyler Locklear Anchor the Middle of the Lineup?

With the trades of Suárez and Josh Naylor, the D-backs are lacking power bats to anchor the middle of their lineup. Their only remaining 20 home run threats are Corbin Carroll and Ketel Marte, their top two hitters. There isn’t much punch in the lineup, and the team knows it.

That’s why they went out and grabbed Locklear as the headliner in the Suárez deal. Midseason swing adjustments have sparked a power surge, reviving his profile as a middle-of-the-order threat. His exit velocity, hard-hit, and barrel rates spiked since the start of June. The D-backs are gambling on those swing changes, and the power surge they’ve led to, having staying power. If that’s the case, he’ll find a home in the cleanup spot as Arizona’s primary run producer.

Defensively, he’s locked in at first base. He’ll have the opportunity to work on his footwork, throwing, scooping, and positioning. As we’ve seen with Christian Walker, a player with the right mindset can develop into an elite defender. While he lacks the range that Walker boasted during his time in Arizona, improved team defense will help the D-backs win at the margins.

If Locklear comes close to his ceiling, they have a 30-homer threat from the cleanup spot that also serves as a functional defender at first base. That’s a privilege the organization has enjoyed for more than a decade with Paul Goldschmidt and Christian Walker.

What Role Can Adrian Del Castillo Carve Out in 2026?

Del Castillo is in an interesting situation due to the lack of a carrying tool in his profile. At the time of this writing, he’s serving as the left-handed part of the designated hitter platoon. However, he’s likely to lose that role once incumbent starter Pavin Smith comes off the IL from his oblique injury.

The reality is that Del Castillo was never going to build enough of a sample size to unseat Smith from that role. A shoulder injury suffered in Spring Training delayed the start of his season with Reno until late June. As a result, he didn’t get the opportunity to fill the role in the immediate aftermath of Smith’s injury last month.

However, the team needs to figure out what they have at the catcher position. James McCann and Jose Herrera are likely to finish out the year with the big league club, but both could be gone by November. McCann will reach free agency, and Herrera is a potential non-tender candidate since he’ll be arbitration-eligible and is out of options. Del Castillo could serve as the primary backup to Gabriel Moreno if the D-backs feel confident enough that his defense has progressed enough to the point where it’s no longer a liability.

The truth is, Del Castillo doesn’t have as strong a bat to be more than a platoon bat if he can’t stick at catcher. That sobering reality means that developing his defense behind the dish is a priority. He has one of the weakest arms behind the plate, leading to below-average pop times to second, so he’ll need to improve his footwork and exchange to deter opposing teams from running wild on him.

There are some examples of solid game-calling behind the plate, like in Wednesday’s series finale against the Tigers. While it didn’t result in a win, Del Castillo called a great game for Ryne Nelson. Nelson struck out a season-high eight hitters and showcased a nasty slider, a pitch he needs to develop to reach his ceiling as the future ace of the staff.

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