BALTIMORE -- On a night when two of the higher-ranked right-handed pitching prospects in the White Sox farm system faced one of baseball’s best lineups, the feedback was clear, if not particularly profound.

To turn stuff with potential into Major League success, Jairo Iriarte and Nick Nastrini need to command it.

Iriarte’s strike-zone issues during the fifth inning of Tuesday night’s 9-0 loss to Baltimore at Camden Yards were minor and entirely forgivable given the occasion of his MLB debut.

With a mid-90s fastball and a slider as the primary offspeed pitch, the White Sox No. 5 prospect received plenty of evidence from the six batters he faced that he can succeed at this level if he can command.

“The ball looked like it was coming out good,” manager Grady Sizemore said. “A little bit of everything that inning. He worked out of a jam. It was a good first outing.”

Iriarte drew three swings and misses against the top of the Orioles’ order, but also issued a pair of walks, the first of which eventually crossed the plate as his only run allowed on Anthony Santander’s sacrifice fly.

His final offering of the night might have been his best, a 94.9 mph fastball that rose just above the zone to get Colton Cowser swinging and leave two aboard.

“I’ve worked a lot to have my mind strong enough, to keep my mind strong, especially in those situations,” Iriarte said through interpreter Billy Russo. “I’m getting better at that, and I have the help of a mental coach too that helps me. This is a work in progress, but I feel like my mind is strong enough.”

While nerves and acclimation to a higher level certainly played a role, his line also aligned with a track record of someone who has a career rate of 4.13 walks per nine innings in professional ball, while never previously pitching above Double-A.

That may be one of the reasons San Diego was willing to package Iriarte in the preseason deal that sent right-handed ace Dylan Cease to the Padres, immediately making the 22-year-old Dominican the White Sox system’s top-ranked right-hander.

The pain was far more acute for Nastrini, the White Sox No. 17 prospect who followed the best start of his big league career with his toughest to date, allowing seven runs while failing to complete two frames.

The 24-year-old has battled those control issues cyclically at multiple levels. And his six walks set the White Sox on a path to extending their losing streak to 12 games before Chicago had the chance to make it through its own batting order.

“He just struggled to get the fastball for strikes,” Sizemore said. “Just a lot of offspeed, went there early and I think they were [looking for it]. When you’re not throwing the fastball for strikes and they can eliminate it, it makes it tough to have a good outing.”

Only four of Nastrini’s seven runs allowed were earned -- with the other three scoring on a dropped fly ball during a scary left-field collision involving Miguel Vargas and Andrew Benintendi.

When Nastrini's evening ended, he had thrown just 30 of his 72 pitches for strikes, marking the third time in his last four starts his strike rate was 50 percent or less.