MESA, Ariz. -- A.J. Puk was drafted as a starter with expectations of one day anchoring Oakland’s starting rotation. His best chance to make an impact with the A’s this year, however, is likely in a completely different role.

When the A’s opened up camp in early March, manager Mark Kotsay indicated that Puk, the club’s No. 14 prospect per MLB Pipeline, would be in the mix for a rotation spot. But as Spring Training has progressed, the left-hander has been used solely in relief, with his sharpest outing yet coming on Wednesday as he fired two hitless innings with one walk and one strikeout against the Reds.

“A.J. and I had a couple of conversations leading up to [Wednesday],” Kotsay said prior to the A’s 5-4 loss to the Royals on Thursday. “A.J. answered some of the things that I wanted to see, which I was very pleased with.”

In those conversations, Kotsay laid out what type of bullpen role he envisions for Puk. The discussions included a comparison to Brewers All-Star closer Josh Hader for the type of blueprint that can be followed.

There are some similarities that exist between the two left-handers. Like Puk, Hader was a power arm who was a starter throughout his Minor League career until he transitioned to what was expected to be a temporary stint in the Milwaukee bullpen. The move became permanent as Hader continued to have success as a reliever, elevating to a setup role and eventually closing out games.

“Left-handed power arm that started as a multi-inning reliever and transitioned into one of the better closers in the game,” Kotsay said of Hader. “He went through that process and earned that role. I think that’s what we want to see from A.J.”

Pitching in relief at the Major League level wouldn’t be anything new for Puk. Mainly due to precaution as he was coming off injuries, Puk has only been used out of the bullpen when pitching with Oakland in 2019 and 2021.

Flashes of what Puk could be as a reliever showed up in ‘19. Back then, he was called up to help the A’s in the middle of a playoff push and proved to be a valuable multi-inning weapon, posting a 3.18 ERA with 13 strikeouts over 11 1/3 innings pitched. Last season, though, his time in the big leagues was a bit more troublesome as he made 12 appearances and posted a 6.08 ERA.

Puk worked with a nutritionist to add 25 pounds to his long, 6-foot-7 frame this offseason. The 26-year-old said that the weight gain was an effort to help quell the recurring injuries he’d dealt with in recent seasons. It also appears to have helped him maintain his fastball velocity throughout his appearances. He’s pitched at least two innings in three of his four Cactus League outings, with a fastball that has consistently sat at 96-97 mph and has reached as high as 98 mph.

“I feel like each outing has gotten better and better,” said Puk, who has allowed just two runs on three hits over his last six innings pitched. “Trying to bring over some of the mechanical stuff I was working on this offseason and take it into the games. I felt pretty clean. Fastball command is there and I’ve thrown in some good sliders.”

Kotsay said he still doesn’t rule out a move back to starting for Puk, possibly as soon as this season if he can get stretched out. For now, the main focus is on finally seeing his long-touted promise come to fruition, regardless of what role that comes in. If it means doing so in a setup or closer role, Puk embraces the new opportunity.

“The high-stakes innings are always fun to be in,” Puk said. “I’ll just try to go in there and keep getting outs to hold the lead for our ballclub to win.”

Jefferies tries out new tech

Daulton Jefferies, who struck out seven batters while allowing five runs on seven hits over 4 2/3 innings against the Royals on Thursday, went through his start utilizing an earpiece-type device that electronically sent signs from catcher Sean Murphy. The technology is developed by PitchCom and is a system that aims to prevent sign-stealing in a much speedier process.

Count Jefferies among the pitchers around baseball who are fans of the experiment, as Thursday marked his second time using it this spring. He also wore it last week during a start against the Guardians.

“I actually really like it,” Jefferies said. “I think it’s gonna be pretty beneficial. It also helps the pace of the game a lot. You’re not putting fingers down. You just hear it in your ear and go. I like that part of it. I know our infielders and outfielders like it, too.”

Asked if he would use it during the regular season, Jefferies noted that there are some tweaks that will probably have to be made, though he expects that will get figured out shortly.

“We’re trying it out right now,” Jefferies said. “I don’t think it can hurt.”