NEW YORK -- Jackson Kowar, the Royals' No. 4 prospect, will head back to Triple-A Omaha with a lot of homework to master and the belief of the Major League staff backing him as he gets to work. The right-hander was optioned Wednesday as the corresponding move for the Royals reinstating lefty Danny Duffy off the injured list.

Kowar struggled in his first stint in the Majors, allowing 10 runs in five innings across two starts and one relief appearance. After dominating in the first month of the Triple-A season, the Royals were able to identify inconsistent parts of Kowar's mechanics that were amplified when he got to the Major Leagues. And Kowar wasn't getting the innings he needed as a member of Kansas City's bullpen, prompting the move to send him back to the Omaha rotation.

"Just telling him a couple things," manager Mike Matheny said. "One is that we're going to need him. Right now, this isn't ideal for a young player to get the repetition he needs and wants. … And it's all going to come down to fastball command. He had that in Omaha, there was no doubt. You don't throw up those kinds of numbers without it. But there were a couple things mechanically, some data that we got from his extension and stride length and trying to get him some more consistency on his changeup and breaking ball."

Kowar's signature pitch is his changeup -- a pitch that, when it's on, Matheny called one of the best right-handed changeups in baseball -- but he struggled to play it off his fastball with the Royals. Batters were hitting .500 off the pitch while Kowar was on the mound with an average exit velocity of 97.5 mph, according to Statcast. Too often, Kowar would leave it in the middle of the plate, and hitters would be ready for it.

"It's about tunneling pitches, but part of the tunneling is how those strides look and where those release points are and how consistent is the extension," Matheny said. "The extension plays a big role in how that ball's perceived once it gets to the plate. So working with the curveball and the changeup and the consistency of the fastball."

Kowar, like lefty Daniel Lynch (the Royals' No. 2 prospect) did back in May, will rejoin the Storm Chasers rotation with a list of tasks to achieve before he can get back to the Majors. But Matheny was clear that Kowar would be back.

"The communication is really just being honest: 'We believe what you do is going to play a big part in us doing what we want to do. We want to see you here. But right now, it's not the right time,'" Matheny said. "And part of the communication is, don't go back with the mindset of, 'How fast can I get back?' Let's go back with the mindset of some clear objectives to improve on for the long haul of his career.

"I know he would do anything he could do to stay here. He fit in well, he was enjoying it, even though he wasn't having the kind of success and production on the field that he wanted. That's as raw of a conversation as you can have. Hopefully he takes it and runs with it, he believes that we believe in him and gets to work."

Staumont's status
For the first time in a week, Josh Staumont took the mound for the Royals in the bottom of the sixth inning during a 6-5 loss to the Yankees on Wednesday night. It had been four games since Kansas City had used the hard-throwing reliever, even though there have been opportunities for him to be used like he has been in the past.

Instead, manager Mike Matheny has leaned on Scott Barlow and Greg Holland, as well as Kyle Zimmer and Jake Brentz, for those high-leverage innings as Staumont works through battles this year, whether it's building up strength from a nasty bout with COVID-19 early in Spring Training or left knee pain that saw him miss time in May.

On Wednesday at Yankee Stadium, Staumont threw 1 1/3 innings before yielding the game to Barlow with one out in the seventh with a runner on base. Staumont had one strikeout, one hit and one walk in his first outing since June 16 against the Tigers. The right-hander threw 18 fastballs and 14 curveballs, averaging 95.8 mph on his four-seamer and maxing out at 99 mph, per Statcast. His 2021 average is 96.5 mph, lower than the 98-100 mph he averaged last year.

But having him on the mound Wednesday was a welcome sight for the Royals -- and the state of their bullpen.

"Just trying to get him feeling strong," Matheny said before Wednesday's game. "And opportunities. We've had some games where guys haven't pitched in a while or some tight games where we've just kept leaning on the same group. But he needs to be in that group where we need to get him right.

"We've seen the velocity fluctuate a little bit, and that's not everything, but I think it's an indicator of when he's feeling good."

Royals rumblings
• Royals outfielder Jarrod Dyson reached 10 years of service time in the big leagues Wednesday, a milestone that is achieved by fewer than 10 percent of players in Major League history. He's spent eight of those years, including 2021, with the Royals.