German Marquez took a perfect game into the sixth inning against the Nationals. (Brad Mills/USA Today Sports)

When major league pitchers talk about “executing” or repeat staples of their jargon such as “command” and “just missing,” they numb those listening to the reality of their craft. Those words do not betray the true difficulty of their duties, the minute margin for error with which they work and the tiny gap between a good pitch and a pitch hit deep.

The previous time the Washington Nationals faced Colorado Rockies right-hander German Marquez, he did not execute, and they punished him. This time, as he pitched the Rockies to a 4-2 win over the Nationals, he did, and they could not do much at all.

Marquez took a perfect game into the sixth inning, and he is not the first to stun the Nationals into futility lately, potent though they are offensively. On a crisp July evening after a day and a half of rain, he dominated.

“He had a very good breaking ball tonight. He was throwing it over for strikes early, and then late he was bouncing them. He was getting strike one,” Nationals Manager Dusty Baker said. “. . . He threw the ball great tonight. Nothing against our hitters, it was just he was beating them tonight.”

Story lines blew around the blustery evening, from a video montage that honored former National Ian Desmond before the game to the meeting at home plate of Baker and Rockies Manager Bud Black, who were both candidates to serve as the manager here. But the matchup of Marquez and Tanner Roark, of pinpoint control and something less, ultimately defined the night.

Roark reemerged since the all-star break, seemingly taking Baker’s advice to heart to start anew, a perfect example of what can happen when command becomes consistent and when executing happens enough to overcome error.

But on Saturday, Roark struggled on the margins again, not lacking command entirely but needing a little more than he had, unable to bury Rockies hitters before they pushed him to deep counts. Trevor Story hit a two-run homer in the second.

Roark allowed two more runs in the fifth, by which time his pitch count rose to 109. In his impressive 2016 season, Roark needed roughly five pitches per out. This season, he is averaging nearly a full pitch more per out, which might not seem like a lot but amounts to 15 pitches over five innings — the equivalent of one more inning per start.

“It’s a tough lineup and a deep lineup, so he was grinding through it,” Nationals catcher Matt Wieters said.

“His pitch count probably got up there but kind of have to sometimes when they have a lineup that deep.”

The Nationals (61-40) could have used another inning from Roark given that they will play a doubleheader Sunday and rookie Erick Fedde will make his debut in the first game, while Edwin Jackson will pitch the second. But his evening ended after allowing four runs in five innings with four walks.

“I don’t mind getting behind 2-0, 1-0, whatever,” Roark said. “I have four pitches I can throw for strikes, and I’m not afraid to throw them in any count. The walks definitely hurt today, but overall I felt pretty good.”

By the time Roark left the game, Marquez had allowed the Nationals nothing — no hits, no runs, nothing.

Funnily enough, the Nationals crushed Marquez in Colorado, vanquishing him with nine hits and eight runs in four innings in April. But baseball ebbs and flows, and the Nationals, without Trea Turner, Jayson Werth, Adam Eaton and Michael A. Taylor, are not the same team they were then.

With a quicker-than-it-seems delivery that made his 98-mph fastball seem faster and his curveball all the more devastating, Marquez cruised into the sixth inning, sending 16 straight batters from one of the league’s best offensive teams back to the dugout.

With the evening quickly devolving into an uncomfortable game of “somebody-just-get-a-hit,” Wieters singled to left field to restore normalcy. Then Howie Kendrick, acquired late Friday night and activated late Saturday afternoon, drove a ball to the gap in left-center in his first Nationals at-bat. Kendrick, the 34-year-old who spent most of this year with the languishing Philadelphia Phillies, earned a standing ovation from the Nationals Park crowd.

As a right-handed bat off the bench — or even in the starting lineup until Jayson Werth returns — the career .290 hitter could prove a significant addition, now and on breezy nights like this a few months from now.

Wilmer Difo drove in two runs with a single that landed inches inside the left field foul line. The margins for hitters are tiny, too, but Difo has been thriving lately. After that hit, he is 21 for 56 (.375) in July, just when the injury-riddled Nationals have needed him most.

Marquez’s night ended after seven innings, two runs and a career-high 10 strikeouts, at which point he gave way to newly acquired reliever Pat Neshek. That Nationals have a few newly acquired relievers of their own, and some thought Neshek might join them in the District.

As it happened, he threw a 1-2-3 eighth. Greg Holland, for whom Nationals General Manager Mike Rizzo had a deal in place this offseason before ownership vetoed it, threw a perfect ninth for his 32nd save in 33 opportunities. In roster construction, as in pitching, near misses mold fates.