MESA, Ariz. -- Coming off a disappointing rookie campaign, Adam Oller wasted no time this offseason searching for answers on what went wrong in 2022 and addressing what he felt needed to be fixed. Early into Spring Training, his stuff on the mound is turning heads.

Facing A’s hitters in live batting practice, Oller pounded the zone with fastballs and unleashed a new pitch he worked on throughout the offseason, leaving manager Mark Kotsay impressed by what he saw.

“This is probably the best Adam has thrown the ball,” Kotsay said on Wednesday. “He looked really good. He looked confident. He threw strikes. From a naked-eye standpoint, his delivery looks like it’s cleaned up. He’s going north and south a lot more and a lot better.”

Throwing strikes may sound simple, but it’s an issue that plagued Oller over a rough 2022 season that saw him post a 6.30 ERA across 19 games (14 starts) with 39 walks in 74 1/3 innings in his first year with Oakland after coming over from the Mets as part of the Chris Bassitt trade last March.

Command was the main quality that put Oller on the radar late as a prospect. His consistent ability to spot the fastball earned him Mets Minor League Pitcher of the Year honors in 2021. Yet upon joining the A’s rotation out of Spring Training last year, the command that was always a strong suit suddenly became a weakness.

“I never struggled with command in my life,” Oller said. “It’s tough that the first time that you struggle with it is your first year in the big leagues.”

Oller identified mechanical flaws that may have caused his issues locating. He also believes something that was just as instrumental to his struggles was his mentality.

From the minute he joined the A’s, Oller said he placed unnecessary extra pressure on himself. Optioned to the Minors after getting hit around over his first three starts, Oller’s confidence plummeted. In each call back up to the Majors that followed, he tried desperately to make every pitch he threw the “perfect” pitch.

Feeling a need to vent about his issues on the mound, Oller began visiting regularly with A’s team psychologist Marc Strickland towards the end of last season. Through those sessions, Oller changed his mental outlook on how he approaches the game.

“I just kind of sat down and talked quite a bit about what was going on in my life and in my head space. Getting some stuff off my chest,” Oller said. “I’ll be the first to admit, I’m one of the last people that would ever go into doing something like that.”

Now looking back at his ‘22 season, Oller views his tough times as a positive.

“I’m glad I had those struggles,” Oller said. “It taught me who I am as a pitcher. I started looking at things positively and taking what was good out of something. You can still take the negatives and learn from it. But taking more of the positives and changing my outlook on things helped out a lot.”

Oller also feels like a new pitcher from a repertoire standpoint. Setting up his offseason workouts at Dynamic Sports Training in Houston, Oller began developing a new pitch. Constantly sending video of his sessions to A’s pitching coaches Scott Emerson and Mike McCarthy, he worked on adding a new breaking ball, which he describes as somewhat of a hybrid between a slider and a curve.

In years prior, Oller said he threw his slider with a traditional grip most pitchers use to generate a seam-shifted wake movement on the pitch. Because of his low three-quarters arm slot, the slider never felt quite comfortable for him. Looking to switch it up this offseason, he came up with his own variation of the grip that has added more of a vertical drop to the pitch.

“It turned into more of a hard curve,” Oller said. “The biggest difference between mine and others right now is, when I’m up to full speed, mine is like 84-87 mph while still keeping the bigger break on it.”

Entering a heated rotation battle this spring with renewed confidence and a new pitch, Oller will get a chance to see if he can translate that into success over the next six weeks.

“All I’m caring about is games starting and showing that I’m not the same person I was in the first half last year. I am who they traded for,” Oller said. “I have a breaking ball now, and I feel like the fastball command is a lot better, so I like my chances.”