Diamondbacks prospect Yilber Diaz gets closer to MLB mix

LOS ANGELES — No hits, 13 strikeouts, 22 whiffs, six scoreless innings. Arizona Diamondbacks pitching prospect Yilber Diaz was dominant on Monday for Triple-A Reno, showing off a 95-98 mph heater with a wicked slider/cutter he has honed this season.

Diaz is 23 years old and has quickly hurtled toward the major league conversation.

Arizona’s No. 16 ranked prospect will likely start Monday’s game against the Atlanta Braves at Chase Field, according to MLB.com’s Steve Gilbert.

Diaz received his promotion from Double-A Amarillo on just June 11 in his fourth minor league season.

Yilber Diaz (@Dbacks No. 16) was on another level tonight!

🔥 Career-high 13 strikeouts across 6 hitless innings
🔥 Tied the Triple-A @Aces single-game K record
🔥 Fanned 7 batters in a row pic.twitter.com/gu3jsbglUm

— MLB Pipeline (@MLBPipeline) July 2, 2024

“He had just been dominating the Double-A level and there comes a point where he just managed the challenge,” farm director Shaun Larkin told Arizona Sports of his promotion to Reno.

“Given their situation at the major league level with our staff, we want to get our best players in the big leagues right, and no one wants to hold anybody back. So when that time is right, and they show they are able to have production at the level they’re at, we move them up.”

Diaz has a 4.03 ERA across 76 innings between the two levels this season, striking out 105 batters (33.2%) with 38 walks. He is still sixth in the Texas League in strikeouts despite having moved on nearly a month ago.

The D-backs called up the group of Brandon Pfaadt, Ryne Nelson, Drey Jameson, Tommy Henry and Slade Cecconi within a season of each other, a corps of young arms the team now relies on with injuries to veterans.

When looking at the next wave to get the opportunity, Cristian Mena debuted on Wednesday, and Diaz may appears to be next in line.

“He commands three pitches, his stuff is fine, but the question is really like any other young pitcher, the execution of the stuff that you have,” Larkin said.

“Whether it’s the crispness of the pitch and or just when you’re using your pitches, how to sequence in the correct way, how to game plan and not let these major league hitters corner you. In terms of stuff on any given night, he could get major hitters out right now … We’ll wait to see what our major league team needs and does, and we’ll go from there.”

Yilber Diaz brought the 🔥 for the @sodpoodles.

The @Dbacks‘ No. 16 prospect struck out a career-high 11 and did not issue a walk over seven scoreless innings. pic.twitter.com/cXZjPhzgWd

— MLB Pipeline (@MLBPipeline) May 3, 2024

Diaz has a three-pitch mix, short for a typical starter. But his fastball command has received high praise, allowing him to complement the heater with his hard slider and a curveball. The curveball remains a work in progress and efforts to develop a change up have stalled, so there is still plenty to learn.

Aces pitching coach Jeff Bajenaru instructed Diaz back in 2022 with High-A Hillsboro, giving him unique insight into the pitcher’s growth.

“With a young kid, is the command going to be there? Is he going to be skirting the zone in Reno where the PCL balls are flying? Or will he attack guys, trust that my stuff is better than your stuff?” Bajenaru said. “That’s exactly what he’s done, but there’s also difference between attacking and throwing strikes. He’s been doing both.”

He said most pitchers struggle a bit when they first get to Reno, but that has not been the case with Diaz who has a 3.27 ERA and 28 strikeouts in 22 innings thus far. It remains very early in his tenure with the Aces, but in a season with so many injuries both to major league and minor league pitchers, this development is one of the more positive within the organization’s farm system.

“He carries himself with a little bit of, I know who I am,” Bajenaru said. “It’s not a cockiness. It’s just, ‘I’m confident. I know what I do well.’ … There’s been a bit of refinement with the fastball command that’s been outstanding. The slider-cutter, he calls it a cutter but I still think it’s a slider velo-wise, it’s deceptive. Hitters can’t make a swing decision on it in time. And the curveball is still, I wouldn’t say it’s there, but it’s a lot closer than it was.”

Diaz becomes Rule 5 eligible next offseason, so this was a key season for the Diamondbacks to evaluate putting him on the 40-man roster.

Mena will not be eligible to return to the majors, barring injury, for 15 days after his option on July 4. Henry started for Reno on Friday, knocking him out of the running to pitch Monday. Jordan Montgomery landed on the 15-day IL retroactive to June 29 for knee inflammation, which opened a slot in the rotation.

Manager Torey Lovullo said after Mena’s option the club discussed using a bullpen game Monday but would likely opt for another starter to take the spot.

“You’re gonna have big league nerves on Day 1, but I think he knows who he is now,” Bajenaru said. “Going out there and giving you seven (innings) on Day 1 one, I don’t know about that. But I think he’ll give you five and keep you in the game. Triple-A to the big leagues are different, but the stuff is still there and I think if the stuff plays, he’ll get it done.”

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