MESA, Ariz. -- The A’s used separate mounds three miles apart to gauge the early spring progress of starting pitchers JP Sears and James Kaprielian on Thursday.

Rotation candidate Sears gave up three runs on five hits over three innings in his second spring start, a 6-1 loss to the Cubs at Sloan Park. What he lacked in fastball command was counterbalanced by a highly effective slider that he worked to refine in the offseason.

Kaprielian, meanwhile, threw 33 pitches in a simulated game at Hohokam Stadium, the first time he faced hitters since undergoing offseason surgery to the AC joint in his right shoulder to alleviate what he called “bone-on-bone” friction that had hampered him for more than a year.

“I feel sharp,” Kaprielian said.

In game action, the Cubs scored all their runs off Sears with hits against his fastball, but they could not touch his slider. Sears struck out Eric Hosmer twice on sliders, and used another, clocked at 84 mph, to induce Cody Bellinger to ground into a double play.

“The slider is analytically a really good pitch,” Sears said. “You don’t live or die by analytics, but that has proven to be something good. I think it plays really well off my fastball. Kind of looks like a fastball for a long time. I throw it with a lot of aggression, and that helps out as well.”

Sears threw what was labeled a slider last season, when he was 6-3 with a 3.86 ERA with the Yankees and A’s. But while he still uses that pitch against right-handed batters, he's now using a remodeled version against lefties.

“Profile-wise, you can call it whatever you want,” Sears said. “Looking at the numbers, I think the slider will play better to lefties. Once I get a good feel for it I’ll throw it to righties as well. It would be great to have it in the mid 80s, because it looks so much like a fastball until late.”

Kaprielian, meanwhile, mixed four pitches -- fastball, curveball, slider and changeup -- in his two “innings,” taking a break in the middle of his session to simulate game conditions.

“[I] like the way things are coming along,” Kaprielian said. “Good to be out competing a little bit, even though it is only a simulation. The numbers on the slider are good. Changeup feels great. Curveball was in there for a strike.”

Kaprielian’s fastball sat in the 93-95 mph range, which he said was fine on a 57-degree day. It averaged around 94 mph last season.

“I’m not really concerned about the velo right now,” he said. “Just happy where I’m at. More importantly, I’m happy that I feel good and could take a step in the right direction.”

Kaprielian was 5-9 with a 4.23 ERA in 2022, as his strikeout rate dropped to 6.6 per nine innings, due at least in part to the shoulder injury. That rate was 9.3 during a healthier 2021, when he went 8-5 with a 4.07 ERA.

The A’s have mapped out a plan to get Kaprielian ready in time for the start of the regular season, and he is following it closely.

“I’m taking things one day at a time,” he said. “I’m doing everything in my power to be ready. Physically and condition-wise I feel great. Things are going great so far.”

Kaprielian is likely to throw a three-inning simulated game on Tuesday or Wednesday, which could be the last step before getting into a Spring Training game.

The A’s appear fairly settled on four starters -- Paul Blackburn, Kaprielian, Shintaro Fujinami and Drew Rucinski -- which could leave room for only one more from a group including Sears, Ken Waldichuk and others.

At the same time, Oakland continues to entertain the idea of a six-man rotation, but a decision is weeks away.

“Some of it goes based on [Fujinami’s] history of pitching in Japan and what he’s comfortable with,” A's manager Mark Kotsay said. “Also looking at how we utilize him to maximize his innings, and where we feel he’d had the biggest impact.

“You also look at how it plays out schedule-wise with off days and how you incorporate those. We do have some young arms that haven’t been through a 30-start season.”