This summer, Ventura pitched for both Double-A Northwest Arkansas and Triple-A Omaha with a combined record of 8-6 and a 3.14 ERA in 26 games (25 starts). He had 155 strikeouts and 53 walks in 134 2/3 innings.
MLB.com ranks Ventura as the Royals' No. 2 prospect. His debut comes as the Royals are battling with the Indians for an American League Wild Card playoff spot.
"This is a highest level of baseball so every time I go out there to pitch, I'm going to give it everything I can in my power to do a good job," Ventura said, with veteran pitcher Bruce Chen translating from Spanish.
Manager Ned Yost said that Duffy, who has made five starts since coming back from Tommy John surgery, felt some forearm fatigue and tightness after his last outing nine days ago against Detroit, when he worked 4 1/3 innings. It's not certain if Duffy will pitch again this season.
"We're going to be real cautious with it, but we're not ruling it out," Yost said.
Duffy said his surgically-repaired elbow is sound.
"We got an MRI done this morning and it showed that there was zero structural damage," he said. "I'm just a little fatigued. It's expected to have setbacks, I'm actually surprised at how good I've felt this whole year without any setbacks. It happens. We've seen it with [Felipe] Paulino, we've seen it with people in the past. It's frustrating at this point because we're in the chase, but I can definitely have some appreciation for their protection of me."
Concern resurfaced in Detroit when Duffy experienced some discomfort while throwing in a practice session.
"The MRI shows that it's just a very mild flexor strain and he's fine," Yost said.
Duffy is eagerly waiting Ventura's debut.
"He throws gas for one. He's fun to watch. Electric stuff, great curveball, really good changeup," Duffy said. "He's a lot like me, he wrangles his stuff, he's going to be lights out and I think he's got every capability to do that. I'm excited to watch him."
"I think we're all excited to see Ventura pitch," Yost said. "I've had my eye on this guy like we all have for the last two or three years watching him come up in the system and I really made it a point at Spring Training to be on the Minor League fields when he was throwing batting practice or even throwing a side."
Ventura will be starting for Kansas City instead of Omaha in the Triple-A Championship Game against Durham and former Royals prospect Jake Odorizzi. Ventura won his only playoff start for Omaha, holding Salt Lake to one run in six innings last Wednesday, after being held out of an earlier start for "undisclosed team violations."
"Sometimes you make mistakes and you have to learn from those mistakes," Ventura said. "I've already apologized to my teammates and I won't make the mistake again."
He declined to specify the mistake as he met with media members.
With Chen translating for Ventura, who is from Samana in the Dominican Republic, the rookie was asked if he could throw as hard as Chen.
The soft-throwing Chen immediately took the bait with a big smile.
"What are you talking about?" Chen said. "Right here, we're averaging about 93 miles per hour. That's above the Major League average so I don't know what you guys are talking about."
Then he translated the exchange for Ventura.
"He doesn't know what to say, he doesn't want to offend me and he doesn't want to lie so he's a good kid, a very good kid," Chen said with a laugh.