SURPRISE, Ariz. -- One pitcher who seemingly has flown under the radar this spring is Royals left-hander Randy Rosario.

Just because Rosario hasn’t been written about or talked about much in the media doesn’t mean the coaching staff hasn’t noticed him.

“I have talked about him internally a lot,” manager Mike Matheny said. “Very impressed with him.”

Rosario, 25, was picked up on waivers last September from the Cubs. He came up through the Twins organization.

Rosario has given up just one hit and no runs through four Cactus League outings, covering 4 1/3 innings. He leads the team with three saves.

“We’ve had no problem putting him into these leverage spots because his heartbeat doesn’t raise,” Matheny said. “He’s got that knack for getting the ball on the ground. And the secondary pitches, that slider, just keep getting better and better.”

Rosario has a career 54 percent ground-ball rate, and that percentage, Matheny believes, will eventually even out his splits. Lefties have hit just .172 against Rosario in his career, while righties are at .338.

Rosario, like Jesse Hahn, is out of Minor League options and is in stiff competition for the one or two open bullpen spots.

But Rosario is proving himself to be more than just a sleeper pick to crack a bullpen that, if the season started today, might look like this: Ian Kennedy, Scott Barlow, Tim Hill, Jorge López, Glenn Sparkman, Trevor Rosenthal, Greg Holland and Josh Staumont.

“I think [Rosario] is just getting better overall,” Matheny said. “His pitches really have a nice downward movement. He can be a valuable piece.”

Junis improving
Right-hander Jakob Junis, projected to be the Royals’ No. 3 starter, missed his last start because of a lower back strain that is considered mild. The Royals scratched him mostly as a precautionary move.

Matheny said Junis threw a live session on Wednesday and looked fine.

“The big thing is he got up [Wednesday] and was fine,” Matheny said. “So no lingering effects. He should be back into the regular schedule soon.”

Keller battles
Right-hander Brad Keller, the Royals’ Opening Day starter last year, was charged with eight runs on seven hits in 1 2/3 innings against the Rockies in his second Cactus League start. He struck out three and walked one batter in the Royals’ 9-1 loss at Scottsdale.

He gave up a three-run home run to Nolan Arenado as part of Colorado’s seven-run second inning. Keller gave up a two-run home run to Manny Machado in one inning against the Padres on Feb. 24 in his first start of spring.

“Results-wise it was not great. I battled out there,” Keller said. “It was just a Spring Training outing, and I’m trying to get my work in. I think that’s why I was out there so long in the second inning.”

Up next
The Royals will play split-squad games on Friday. The game in Tempe at 2:10 p.m. CT is a makeup of the Feb. 22 game that was rained out. Right-hander Brady Singer, ranked by MLB Pipeline as the Royals' No. 2 prospect, will start the game. Right-hander Jackson Kowar, the No. 4 prospect, will also pitch in Tempe. Left-hander Daniel Lynch, the No. 3 prospect, will start the home game at Surprise Stadium against the Angels at 2:05 p.m. CT.