Astros pitcher Lucas Harrell peels himself off the mound after nearly being tagged by a line drive in the first inning as the Nationals earn a sweep in Houston. (Bob Levey/Getty Images)

The most worn description of Jordan Zimmermann sells him woefully short. Zimmermann is consistent, yes, the same way you would call space shuttle launches punctual: The supposed compliment reduces him to something less than he is. Zimmermann overwhelms hitters, dominates games and belongs on the short list of best pitchers in the major leagues. He is, most succinctly, an ace.

Thursday night at Minute Maid Park, Zimmermann gashed through the Houston Astros, lifted the Washington Nationals to a 5-0 victory and added to his case as a potential Cy Young Award candidate. Zimmermann tied his career high with 11 strikeouts in six scoreless innings. He walked none, allowed three hits and lowered his ERA to 2.35, second in the National League.

“He competes, he doesn’t care, he’s not afraid,” pitching coach Steve McCatty said. “He comes after you. He does what he does, and he doesn’t change. It’s not like he’s a plodder — more like a racehorse, a thoroughbred.”

Michael Morse drove in three runs and extended his hitting streak to 18 games with two homers, the first of which appeared to be bound for Phoenix ahead of the Nationals. After three harrowing wins over the worst team in the majors, Zimmermann ensured the Nationals would complete their sweep of the Astros with minimal drama.

With their sixth straight victory, the Nationals matched their longest winning streak of the season. As they dispatched Houston, the Nationals ran the best record in baseball to a 26 games over .500 at 69-43, 4½ games better than second-place Atlanta in the National League East and at least three games clear of every team in baseball. Every win provides a new height.

On Thursday, Zimmermann handled the heavy lifting. He dared the Astros to hit his mid-90s, four-seam fastballs. In the first inning, he threw nothing else. “Until they prove they can hit that,” he said, “I’m just going to keep throwing it.”

To keep them honest, he fired his devastating slider. Zimmermann threw 65 heaters, 20 sliders and only two of anything else. The Astros could not hit his best two pitches, and so he did not bother with anything else.

“I love it,” said Kurt Suzuki, who caught Zimmermann for the second time after being traded from Oakland. “He runs that fastball in there at the upper 90s. The impressive part is, he goes right at you. He ain’t trying to trick you. He ain’t trying to nibble. Here it is. Hit it.”

Zimmermann’s simple, attacking approach overpowered Houston. The Astros swung and missed at 16 of his 87 pitches. He struck out Jose Altuve, one of the best contact hitters in baseball, lunging at a 96-mph fastball over the outside corner. In the fifth, he struck out the side in 16 pitches.

“He’s in attack mode coming out after guys,” Manager Davey Johnson said. “He’s a bear out there.”

Zimmermann allowed an infield single to Marwin Gonzalez with one out in the sixth. Pitching from the stretch, he reached another level. He struck out Steve Pearce swinging at an 85-mph slider. He threw Justin Maxwell an 86-mph slider, a 93-mph fastball and an 84-mph slider. Maxwell swung and missed at all three, flailing at the last one as it buried in the dirt.

Clearly, Zimmermann had more strength and energy — more everything — in reserve. But Johnson pulled him after six innings for a pinch hitter. Johnson has recently pulled Zimmermann from starts before his pitch count surpasses the low 90s. Before his last time out, Zimmermann had felt tightness in his shoulder as he warmed up, and the Nationals pushed him back for two days of extra rest.

“I could have definitely went out there in the seventh,” Zimmermann said. “I felt fine. But we don’t want to push it and injure it more than what it is. I’ll be fine in five days.”

The Nationals have reason to protect Zimmermann, hands down their best pitcher this season. His record is 9-6 “but you can’t judge him on that,” McCatty said. “Because his stuff is really unbelievable.”

Only Ryan Vogelsong of the San Francisco Giants, at 2.27, has a better ERA than him in the NL. Of Zimmermann’s 23 outings, 20 have been quality starts. He has yielded either zero or one run in eight of his past nine starts. He now has 4.35 strikeouts for every walk issued. Scroll down his stat sheet and pick any number you want.

“Sure, he belongs in the [Cy Young] conversation,” McCatty said. “I’d match his stuff up with everybody else.”

Thursday, the Nationals took care of all the offense they needed with two runs in the fourth inning, a rally started by Roger Bernadina, who went 3 for 4 starting for Bryce Harper.

For good measure, in the sixth inning reliever Mickey Storey threw Morse an 0-1 cutter, and he crushed it in the general direction of Corsicana. The ball soared high to left field and smacked off a metal sign hanging about 40 feet above the top of the wall. The solo shot gave the Nationals a 3-0 lead.

“Yeah, that was a good one,” Morse said.

Morse added one more homer, a slicing drive to right-center, in the eighth off reliever Fernando Rodriguez. The fourth two-homer game of Morse’s career upped his season total to 10.

“Today was more the way he swung the bat last year,” Johnson said. “Since he came back, it looks like he’s almost sitting on the breaking ball. Today, he was attacking the fastball. I like that.”

Morse’s monster game gave the Nationals’ bullpen room to breathe, but the night belonged to Zimmermann. At this time last year, he stood a handful of innings away from reaching his prescribed limit in his first full season back from Tommy John surgery. He now stands at the top of baseball’s best rotation, a pitcher who is so much more than consistent.

“I feel like I have a pretty good season going right now,” Zimmermann said. “I just want to finish strong and not fall off towards the end. Whatever awards are out there, hopefully I get mentioned in some of them. But the main goal right now is making the playoffs.”