CHICAGO — Less than a week ago, Cade Horton stood at his locker in the clubhouse at Daikin Park in Houston and delivered a blunt assessment.

“I got my ass kicked,” Horton said after surrendering seven earned runs against the Astros. “It was the first time I wasn’t able to slow the game down. I let my emotions get the best of me today and I have to learn from it and move on.

“I’ve been in this spot before and you have take it for a grain of salt and learn from it and move on.”

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Horton vowed to be better and use that as a growth opportunity. Man, did he ever.

The rookie turned in his best outing of his young career, shutting out the Cleveland Guardians over seven innings, allowing five hits, a pair of walks and striking out five in the Cubs’ 1-0, walk-off win in 10 innings.

“That’s what this is all about,” Cubs manager Craig Counsell said after the game. “I think it’s making adjustments. It’s about leaving it behind you and staying in the present and not letting it carry over.

“And it’s learning from failures or things you don’t do well. When you’re clear-headed, I think you have the great ability to do it, and that’s what Cade showed tonight.”

Most of the adjustments Horton had to make from last Friday to this Thursday hardly had to do with mechanical changes or pitch sequencing.

“I think the biggest thing was the mental side of the game and just slowing the game down and being in control and living pitch-to-pitch,” Horton said after the win. “I think that was the biggest difference tonight.”

He did, though, fine-tune his arsenal against a left-handed heavy Guardians lineup. They had eight left-handed or switch hitters in their lineup, and instead of relying on his fastball-sweeper mix that he’s primarily used this season, Horton used his changeup off his fastball to keep the Guardians at bay.

Horton threw his fastball 53 percent of the time and his changeup usage was at 24 percent. The off-speed pitch garnered eight whiffs and three of his five strikeouts ended with that offering.

“I like facing lefties, just with my fastball shape,” Horton said. “The changeup was really good today. I had a good feel for it, so just continuing to develop that and become more comfortable with it.”

It’s a pitch he’s admittedly been trying to pinpoint all season but felt a cue click for him in his outing against the Miami Marlins on May 21. He used the pitch less after that outing before spiking the usage on Thursday.

“It was just more a feel of getting the ball out in front and not trying so much to pronate it more, honestly, trying to supinate to get that axis to kick on the ball,” Horton told Marquee Sports Network last week during the Cubs’ seven-game road trip. “That was the main thing was just feeling it out in front and not trying so hard to turn it over.”

Unlocking that pitch can help him be a more well-rounded pitcher and help his strong fastball and wipeout sweeper. But as a young pitcher, the mental side will be just as important as grips, sequencing and any other physical trait on the mound.

Thursday was a prime example of that.

“It’s huge,” Horton said. “Success builds confidence and so just continue building on that. Enjoy it today. But tomorrow, it’s back to work. I got another start in five days. And so just go back to work.”

It’s what he did after the Houston start. And he’ll do it after the best outing of his career, too.

“Outings like [the one in Houston], they sit for a little bit,” Horton said. “But it’s all about continuing to put in work each and every day. You can’t go back and change it, but what you can do is learn from it, and so just taking those things and learning from it and applying it to the next start.”