SAN DIEGO -- In 2020, Chris Paddack endured the worst baseball season of his life, ending in two of the biggest disappointments of his career -- and then he spent the offseason reminding himself of it every single morning.

Taped to the wall when Paddack opened his bedroom door was a picture of him at his lowest point as a big leaguer -- walking off the mound in the third inning of the Padres' first postseason game in 14 years, having allowed six runs against the Cardinals in Game 1 of the National League Wild Card Series.

Paddack doesn't want to forget that feeling. Because he doesn't ever want to live with it again.

"First playoff game in 14 years, you go out there and let up a [six]-spot, it was just like you let the whole world down," Paddack said. "I really think if I wouldn't have experienced that last year, I wouldn’t know that feeling. ... Now, I know that feeling. I wouldn't be able to do what I'm doing now."

What Paddack is doing now is reinventing himself as a pitcher. He had to. Paddack burst onto the scene in 2019 with one of the best rookie seasons for a pitcher in Padres history. Then, he took several steps back in '20.

Paddack was San Diego's Opening Day starter last season, but he never lived up to that billing. He posted a 4.73 ERA in 12 starts before his Wild Card Series letdown. Then, Paddack was passed over for a start in the NL Division Series against the Dodgers. (Paddack was scheduled to start Game 4, but the Padres were swept in three.)

Humbled for perhaps the first time in his baseball career, Paddack entered the offseason determined to use those two disappointments -- his start against the Cardinals and his absence against the Dodgers -- as learning experiences.

“That’s part of becoming a Major League pitcher,” Padres pitching coach Larry Rothschild said. “Right away in the winter, we talked. He was immediately on top of all of the stuff we talked about and got right to work with it."

Paddack is the first to say he's not the finished product. He owns a 4.10 ERA across 13 starts this season. But that includes a 3.35 mark since the start of May, entering his outing against the D-backs on Friday night.

Paddack’s recent success is a product of some notable changes. His curveball is, at long last, a reliable Major League offering. His fastball more closely resembles the 2019 edition than the eminently hittable '20 version.

But more than anything, Paddack says, the difference is mental.

"The curveball has helped, especially now that it's in opposing teams' scouting reports," Paddack said. "They can't just sit on a changeup or whatever. That definitely plays a role. But a lot of it is up here."

Paddack pointed to his head and was quick to note that -- no matter how much bite on his curveball, no matter how much life on his fastball -- his biggest improvements have been mental.

"You struggle over and over, you start believing the stuff you're hearing about yourself," Paddack said. "I got myself in a big hole there in 2020. I wanted to be the ace. I wanted to be the guy."

That's no longer the case. In fact, Paddack is quick to note the added benefits of having a rotation full of veterans. Yu Darvish, Blake Snell and Joe Musgrove weren't in San Diego last season. That's a wealth of knowledge that Paddack has done his best to extract -- and a much less prominent role for him at the back of the rotation.

Last season, the Padres asked Paddack to headline their rotation. This season, they're asking him to be a reliable back-end starter. Paddack has been up to the task.

"He faced some trials and some challenges," San Diego manager Jayce Tingler said. "He's responded exactly how you want to see. He went to work this offseason. He stayed diligent. He hasn't gotten too high on some of his good starts. He's truly gone start to start, and he's just killing what's in front of him."

That's a particularly apt description of Paddack's change in mindset. He's taking care of what's in front of him. Paddack's starts haven't been flawless. But the innings that spiraled on him last season? They haven't been spiraling on him this year.

The difference?

"Last year, it was that doubt, that negative self-talk, instead of, 'OK, I'm going to grit my teeth right here, and I'm going to find a way,'" Paddack said.

These days, Paddack is finding a way. And that was the purpose of that picture taped outside his bedroom door. That game against the Cardinals -- like Paddack's entire 2020 season -- spiraled.

All because he wasn't in the right mental space.

"I always had success," Paddack said. "I was always the top guy, and I never struggled. When I struggled for the first time, getting my teeth kicked in, you panic. I panicked. I didn't know how to handle that."

He does now -- and he's convinced he's a much better pitcher for it.