The Washington Nationals rolled into Miller Park on Friday night as the hottest team in baseball, riding high on a six-game winning streak and a growing sense of certainty about their spot at the top of the sport. They shared the best record in the majors, and they wanted more. “We haven’t done nothing yet,” Manager Davey Johnson said.

And then less than five innings into a 6-0 loss to the Milwaukee Brewers, Johnson essentially conceded. He pulled Ross Detwiler after 42 / 3 innings and only 83 pitches, not wanting to ratchet up his pitch count for a cause he considered all but lost. He watched the way the Nationals’ previously scalding offense flail against 27-year-old rookie sensation Mike Fiers, and he could not envision their winning streak growing to seven. The Nationals’ momentum screeched to a halt.

“I was actually pleased with the way Det threw the ball,” Johnson said. “That was going to be a game where I’m not going to let him throw a lot of pitches when it doesn’t look like we’re going to have much of an attack. I’m not going to push him in a game where I feel like we’re going to score two or three runs.”

Johnson made his determination based on how the Nationals approached Fiers, who made his 10th career start. Fiers bedeviled the Nationals with his funky delivery, high release and rainbow curveball. They managed four hits off Fiers in 61 / 3 innings, and he struck out nine.

Detwiler came into the night chasing two spectacular starts, having allowed one run over 14 innings. He pitched well again until two spasms of inadequacy ruined his night. The Brewers scored all of their runs off Detwiler in the fourth and fifth innings, both frames he began with two quick strikeouts before unraveling.

As Johnson strided to the mound to remove Detwiler, the starter talked into his glove, and he kept his mitt over his mouth as he walked off the field and into the dugout. He had allowed seven hits and walked one while striking out five.

For Detwiler, both the pitches he did not locate and the timing of his exit ate at him. He left a runner on base, and needed just one more out to reach a full five innings.

“Everything,” Detwiler said. “I don’t want to come out of the game ever, especially in a spot like that. But I put us in a hole early, and it’s tough to dig out of that hole.”

Detwiler watched as Craig Stammen allowed one of his runners to score — bringing his total to four — and then as Aramis Ramirez put the game out of reach with a two-run homer off Stammen.

Detwiler wanted to make one adjustment for his next start. He felt at times on Friday he overthrew, which caused his pitches to elevate. He wanted instead to pitch with a better downward angle, which would prevent his pitches from sailing high over the plate. “Another four days until the next one,” he said. “I don’t think I was that far off. There’s not much to change.”

The Nationals (59-40) entered Friday night not only with six consecutive victories, but also an incredible, uncommon streak. According to ESPN’s research, they were the third team since 1900 to win six straight while scoring at least five runs and holding their opponent to two runs or fewer in each game. They outscored their opponents 40-12 over the win streak.

Their offense had scored 117 runs in July entering Friday, more than any team in the majors, but they could not figure out Fiers. He seems to grab the ball from his back pocket during his delivery, then pulls it over his head. The Nationals are not alone in their futility against Fiers, who has a 1.77 ERA. Opponents may solve him when they see him again, but in his first trip through the league, he has been a storm.

“You don’t really see someone that’s that high up,” shortstop Danny Espinosa said. “It’s kind of deceiving. Balls that you thought were lower ended up at your knees, and balls that you thought were at the knees were higher than what you thought. No one’s had at-bats against him. No one knows what he wants to do. Tip your hat to him.”

Detwiler matched Fiers zero for zero in the first three innings. He began the fourth inning by striking out Carlos Gomez on a check swing and whiffing Ryan Braun with a curveball that dove across the plate and nearly hit him in the ankles. A third consecutive dominant start seemed to be in the offing.

Without warning, Detwiler momentarily came unglued. Ramirez ripped a ball into the right-center gap, which Bryce Harper nearly caught with a full-out slide. Corey Hart followed and smoked an 0-1, 95-mph fastball over the left field fence. The Brewers led, 2-0.

“He’s a good power hitter,” Detwiler said. “He’s going to turn on it.”

In the fifth, Detwiler again struck out the first two batters he faced, giving him five strikeouts. The Brewers mounted another two-out rally, one Detwiler would not survive.

Norichika Aoki slapped a double down the left field line, then stole third as Detwiler paid scant attention to him. Gomez ripped a single into left, putting the Brewers ahead, 3-0. Johnson had seen enough, and he came out to give Detwiler an early hook.

“He was throwing the ball good,” Johnson said. “He probably didn’t understand that one.”

The game included one bright spot, scoreless innings by both Henry Rodriguez and Drew Storen. In the Nationals’ new reality, of course, silver linings do not count. In Atlanta, the Braves thumped the Philadelphia Phillies and cut the Nationals’ lead in the NL East to four games. The Nationals could only come back Saturday and hope to start a new streak.