Mitch Keller entered his start on Tuesday on the heels of one of the shortest starts of his young career: a 2 1/3-inning loss that required 83 pitches to complete. But Pirates general manager Ben Cherington knew the effort Keller was putting in behind the scenes.

“He’s frustrated by the inconsistency. He’s working hard,” Cherington said. “I really believe in what he’s working on. It's important that he continues to pitch.”

The hard work was apparent in the gains Keller showed in a 2-1 win over the Padres on Tuesday night at Petco Park. While Keller’s line wasn’t too different from his other high spots this season -- 5 2/3 scoreless innings with two hits allowed and two walks -- it was the regularity of shutdown innings that stood out among the rest.

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Keller issued a four-pitch walk to Jurickson Profar with one out in the first inning, a sign which has normally spelled short outings defined by command issues and an inability to put away batters. But the right-hander buckled in, threw strikes and struck out Manny Machado swinging in the next at-bat.

“The whole mentality was just, 'Screw it, next pitch,'” Keller said. “I think I did pretty well with that tonight. When someone got a hit or something like that, I flushed it and went right after the next guy.”

Keller gave up his first hit on a one-out single by Jake Cronenworth in the second, but then that mentality came flooding back.

Keller retired the next 12 batters in a row, inducing plenty of weak grounders and lazy fly balls. That span of dominance was snapped by a one-out single from Trent Grisham in the sixth. And though Keller got the second out of that inning, he walked Manny Machado to put runners on the corners and end his night.

After left-hander Sam Howard stranded his 10th straight inherited runner of the season, Keller and the Pirates could breathe a sigh of relief and celebrate the spotless line the young hurler produced.

“He’s actually one of my favorite pitchers right now,” said third baseman Erik González, who scored the game-winning run from second base on a chopper to second in the sixth, via an interpreter. “To be honest with you, I know that he’s nasty. He’s got good stuff.”

The Padres handed Keller one of the most lopsided losses of his young career on April 15, when they tagged him for seven runs on nine hits and three walks in 3 1/3 innings. Despite a few bad pitches, including a slider to Machado for a three-run homer, Keller felt like he was executing close to how he wanted in that outing.

Those were more than just reassuring words after a tough loss. Keller went back to his fastball at nearly an identical rate in this start, throwing it for 69 percent of his pitches vs. 63 percent his first time vs. the Padres. He said that was the game plan -- a lot of fastballs, mixed in and out -- and he didn’t shake catcher Jacob Stallings once, trusting himself to locate his heater wherever Stallings’ mitt was set.

“I just followed along,” Keller said. “Whatever he was throwing down, I was just going for it. Whenever we get into something like that, it’s really special, because there’s just no questioning what he’s putting down.”

One minor tweak was an uptick in Keller's curveball usage. After throwing his slider more frequently against San Diego last time, he threw his curve for 16 offerings vs. only four sliders in this start.

“I think because he commanded the fastball and the curveball [came] out of the same slot, it enabled it to play better,” Pittsburgh manager Derek Shelton said.

Keller has pitched in the big leagues for three seasons, so to some, he feels like an everyday Major Leaguer at this point. However, this was only the 25-year-old’s 22nd career start -- shy of the typical full-season slate of 25-30 starts for a normal starter over a 162-game season.

“A lot of guys have gone through this stage with about that much experience,” Cherington said. “There are guys in our division with other teams who have gone through this kind of thing. We have to keep that in mind and just continue to support him.”

The Pirates will continue to pour into Keller, who was the organization’s No. 1 prospect as recently as 2019, and give him the starts to grow into his game in the big leagues. They know what he’s capable of when he’s at his best. Now, the goal is to have him more consistently pitch to that level.

“We have to help him get past the young Minor League prospect stage and to be a consistent, effective Major League pitcher,” Cherington said. “He certainly has the ability to do that.”