SURPRISE, Ariz. -- The first two two-strike sliders Kris Bubic threw Monday were left up enough in the zone that the D-backs' hitters sliced them for hits, an infield single and a single through the gap into right field.

The third was the one Bubic was looking for, and Jose Herrera swung through it for strike three to end the inning and Bubic’s spring debut.

“Tried to really emphasize it down and below the zone,” Bubic said. “It feels good, and I’ll continue to get reps with it as we go on.”

Bubic threw a scoreless inning in the Royals’ 10-1 win over the D-backs at Surprise Stadium, the lefty’s first Cactus League action this spring because of left shoulder soreness that slightly delayed his throwing program this offseason. Healthy now, Bubic was eased into action as a precaution, and it’ll likely put him an inning or two behind by the end of camp.

“I know he said he felt good, which is the most important thing,” manager Matt Quatraro said. “It looked like he was really going after the hitters. … The pitching guys were saying his delivery was good, and he’s working down the mound the right way.”

For the second consecutive spring, Bubic is focused on adding a slider to his arsenal. He worked on the pitch last spring, but he never threw the pitch in a regular-season game. This year, after talking to pitching coach Brian Sweeney this offseason, Bubic is committed to working a slider into his pitch mix.

“I think I have a really good idea of what I want it to look like,” Bubic said. “It’s something I wanted to implement the past couple of years, but now, given the rest of my arsenal and how the pitches work with each other, I think I have a much better idea of what the shape needs to be, what the velocity needs to be and how it fits into my arsenal. Not that I didn’t know that before, but maybe you’re experimenting too much that you don’t settle on one thing.”

The goal is for Bubic’s slider to give him a weapon against lefties, who slashed .372/.459/.611 in 134 plate appearances against him last year. It’ll give him velocity separation from his changeup (80.7 mph average in '22) and curveball (79.4 mph) -- the slider sat around 85-87 mph on Monday. 

“And hopefully, a good tunnel off the fastball,” Bubic said. “The curveball, a lot of times unless you throw it really hard, it’s hard to minimize the hump in that pitch, the pop out of the hand. So just minimize that and have another weapon that’s a little more neutral, little more on a fastball plane out of the hand.”

Singer tunes up for Team USA
Brady Singer made his final start before World Baseball Classic exhibition games begin later this week, striking out five in three scoreless innings. Singer allowed singles to the first two batters, then threw a perfect outing from there.

The eight changeups he threw, though, were the biggest takeaway.

“The changeup was probably the best it’s ever been in my whole entire career,” Singer said. “I had a really good feel for it. The movement on it was better than it’s ever been. It felt good in the 'pen, then out in the game, I started throwing it more and felt good with it.”

The improvement of Singer’s changeup was crucial to his success last year, but he still needs to develop the pitch to stay unpredictable and be a true three-pitch pitcher. He’s been tinkering with it this spring with the Royals’ pitching coaches and likes the movement and velocity it’s getting.

Singer’s next outing will be in a Team USA uniform. Pool play begins Saturday at Chase Field in Phoenix.

“It’s going to be unbelievable,” Singer said. “After this outing, the confidence is good, and I’m ready to compete. I’m ready to get out there and get going.”

Royals rumblings
• Maikel Garcia got his first start in center field as the Royals try to increase their depth in the outfield and figure out ways for the No. 3 prospect to get playing time with Bobby Witt Jr. entrenched at shortstop. There wasn’t much action out there Monday, but Garcia easily got to a ball hit into the right-center gap.

“I’m glad he got the one ball in the gap,” Quatraro said. “He looks natural. If you didn’t know any different, you’d think he’s playing out there all the time.” 

• The Royals have signed all of their pre-arbitration players to 2023 contracts after agreeing with the final five players on Sunday afternoon.