WASHINGTON — Mitchell Parker made his way to the bullpen with a look of focus and determination. This outing against the Brewers was going to be different. He made the final warmup throws, took a breath and began his redemption.

The 24-year-old spun six scoreless frames, allowing three hits and three walks while striking out three in the Nationals’ 4-3 win on Sunday afternoon that secured a series victory at Nationals Park. The southpaw transformed into a different pitcher from the one who faced Milwaukee on July 13.

Parker said he moved past the previous outing to focus on what he needed to do and entered the game with a clean slate.

“When you look back on that game, he fell behind a lot, and [when] he had to throw a strike, they were on it,” manager Dave Martinez said before Sunday’s game. “So he’s got to continue to work ahead. … I thought DJ [Herz] did a great job [Saturday] pounding the strike zone. [Parker] has to do the same thing today. His stuff plays. We saw him when he was really good. We saw him when he got hit a little bit. It doesn’t mean that the stuff isn’t good. You just gotta understand that he’s got to work ahead.”

The first frame was not the ideal start, with Parker’s fastball velocity sitting around 89 mph. Seeing the dip, Martinez became concerned.

“I wanted to know why but it’s hard to talk to a guy when he’s out there,” the manager said. “All of a sudden, he figured it out and the velocity was 92-93, where he’s supposed to be. He was getting underneath the ball, trying to push the ball a little bit, and realized it right away. He started getting on top and driving the ball and it was beautiful.”

The issue was something Parker had dealt with in the past, so when it cropped up again, he made sure to “get on it quick and be able to get on top of it.” He also had some early trouble executing the location of his pitches, which he quickly corrected.

The adjustments Parker made helped him to cruise through the rest of his outing, silencing the Brewers’ bats. The New Mexico native threw 87 pitches (52 strikes) in the dominant outing, nearly double the 46 pitches he threw over just two-thirds of an inning in his rough start on July 13, a game the Nationals came back to win at American Family Field.

“You can blame our offense, we didn’t get anything going,” Brewers manager Pat Murphy said. “Give Parker credit, he pitched well, mixed well when he had to, and made quality pitches at the big times. But we did hit balls right at people. That’s baseball. No excuses. That’s baseball.”

Parker’s outing kept the Brewers in check while the Nationals’ offense took advantage. Similar to Saturday, Luis García Jr. walked up in the first inning with two outs. This time, he knocked his 13th home run for the first run of the game, his second long ball in two days.

Washington added to the lead in the sixth with a three-run rally. CJ Abrams and Juan Yepez swatted back-to-back singles to put themselves on base. García struck out looking, but Keibert Ruiz followed up with an infield single to load the bases. The stage was set for James Wood, MLB’s No. 2 prospect, per MLB Pipeline, and he laced a three-run triple to left field — the second triple of his Major League career.

“I was trying to put a bat on the ball and trying to make something happen there,” the outfielder said. “I’m trying to treat it like [just] another at-bat. I know it’s not, that there are runners in the scoring position — it’s an important part of the game. But I try to treat it [that way], approach-wise, and go with my plan.”

Parker put up the zeros on the board and the offense scored the insurance runs in the sixth, which allowed the Nationals to maintain the lead when Milwaukee made a late comeback attempt. The deficit was closed to one run by the Brewers after a three-run eighth, but the Nationals held them there.

“They’re a good team, but we’ve been saying all year — we feel like we can play with anybody in the league,” said closer Kyle Finnegan, who notched his career-high 30th save. “We’ve won both series against them this year and they’re looking like a playoff team, so it’s just a testament to what we have in this clubhouse.”