PEORIA, Ariz. -- It's been precisely one year since Jackson Merrill made his big league debut as a wide-eyed 20-year-old in Seoul. And, well ...

"It's crazy," Merrill recently said, "how much things change in a year."

In some ways, things have changed extraordinarily. Merrill is coming off arguably the greatest rookie season in Padres history. He seems destined to bat third in their starting lineup this year, between Fernando Tatis Jr. and Manny Machado. Merrill is already a star -- and could be on the verge of superstardom.

Yet, in some ways, things haven't changed at all. At the core of it all, he's still the very same Jackson Merrill -- the kid who wouldn't want to be anywhere else but on a baseball field.

Two months ago, when the Padres held a strength camp for their prospects at the Peoria Sports Complex, Merrill was on hand nearly every day. It didn't matter that he'd graduated to the big leagues. Merrill was there to watch those Minor Leaguers and to get his own work in.

"I can't get enough of this, man," Merrill said. "I just want the season to start."

Nobody would've faulted Merrill for spending extra time at home in early January. But Padres evaluators touted the impact of having Merrill at the camp.

He wasn't the only big leaguer on hand. A couple veterans vying for roster spots were there, too. But a year ago, Merrill was at the very same camp. Then, after a season in which he reached the All-Star Game, racked up crucial hits in the playoffs and finished second for the NL Rookie of the Year Award, Merrill was right back in Peoria in early January.

Without trying to do so, Merrill set quite an example for those prospects. But he says his thinking was simpler than that. Merrill wanted to be back on a baseball field, and if his offseason preparation worked last year ...

"I didn't want to change anything," he said.

That doesn't mean Merrill's build-up to his sophomore season has been the same. A year ago, Merrill played nearly every day in the Cactus League. He was learning the nuances of a new position and trying to make the roster.

"Going into the season it was just such a different thing," Merrill said. "This year, I'm going in, I'm ready to go. Last year, I don't even know if I'm on the team. I'm going every day. This year, I'm just focused on the 162 and beyond. I feel more ready."

Which is a funny thing for Merrill to say, because he seemed pretty ready last year. But he's clearly not one to rest on his achievements.

"Last year was great, and it was fun, and there were so many cool moments," Merrill said. "But overall, I can be better. Being more consistent is where I want to be. I had slumps -- nothing huge. ... But this year, I'm more focused on: Let's stay consistent. Let's find a way to walk, to get on base. Let's still impact it."

Again, Merrill is selling himself short. He hardly slumped at all last season. And when he did, he brought tremendous value -- on the field with his defense and off the field with his energy.

But the point is: He thinks he can get better and is striving for it. The Padres have taken note.

"Greatness at anything requires a lot of things," said manager Mike Shildt. "The preparation, the natural skill set, the desire to be great. And the hunger, for when you have success, to want more. ... For Jackson, he's a hungry, competitive athlete that also enjoys the process of playing. It's a great combination."

Merrill credits his family, his friends and his girlfriend for keeping him grounded. For keeping him the same Jackson Merrill. At Padres FanFest, he said he still tries to live his life in almost exactly the same way that he did a year ago -- even if it means getting recognized a bit more frequently when he's out and about.

Merrill is one week away from a second consecutive Opening Day start. The circumstances around this one are wildly different. By now, Merrill has proven himself more than capable in center field. And he won’t be hitting ninth.

“Obviously there's comfortability in knowing I'm probably moving up in the order, probably going to have more opportunities,” Merrill said. “It’s eye-opening. It's exciting. But at the same time, I'm relaxed. I'm here. There’s nothing else that’s going to change my performance but me.”