Chicago’s Starlin Castro is called out at home after a stellar tag by outstretched catcher Kurt Suzuki in the second inning, with an outfield assist courtesy Roger Bernadina. (Jonathan Newton/The Washington Post)

The Washington Nationals’ frustration and angst of April have given way to a carefree May, the pitching and defense settling into a groove, buoyed by an emerging offense.

Against the lowly Chicago Cubs on Friday night at Nationals Park, the team turned in another crisp performance for its fifth straight victory, a 7-3 win. The streak has followed a rare team meeting by Manager Davey Johnson in Pittsburgh on May 4, during a series one Nationals player signaled as a turning point in the young season. After a 13-14 April, the Nationals are 7-1 in May.

The Nationals scored at least five runs for the fourth time during their winning streak. Ian Desmond had his biggest offensive output of the season, finishing 3 for 4 with a two-run home run and run-scoring double. Kurt Suzuki and Danny Espinosa each drove in two runs. Adam LaRoche smacked two hits, finally raising his batting average above .200. Strong defensive plays helped Ross Detwiler through 62 / 3 innings on a night when the left-hander wasn’t at his best.

The Nationals pounced on Cubs starter Jeff Samardzija in the fourth and fifth innings, chasing him from the game. LaRoche singled to lead off the fourth inning and Desmond drilled an 0-1 slider over the left field fence to break open a 2-2 tie. The hitter that carried the offense through the early weeks, Bryce Harper, missed Friday’s game after a minor procedure to remove an ingrown toenail from his right big toe but the lineup still produced.

“It’s big when your three-hole hitter’s out of there and you score a bunch of runs,” Johnson said. “That’s big.”

In the fifth, the Nationals were back to tormenting Samardzija, the Cubs’ opening day starter. Ryan Zimmerman drew a two-out walk and LaRoche singled to right. Both then scored on back-to-back doubles from Desmond and Espinosa, the latter a screaming ball off the center field wall. Suzuki drove in two runs on a double in the second inning.

“Just the way the game was going tonight, it seemed like everyone was hitting barrels,” Desmond said. “Hitting is contagious. Once one guy gets going, everyone kind of feeds off that. So it was a good night.”

Because of injuries to Harper and Jayson Werth, who is headed to the disabled list with lingering hamstring cramping, Roger Bernadina made a start in right field. His offense has struggled because of the sporadic playing time. Defensively, however, he has been strong.

He made a slick diving catch in the ninth inning of Wednesday’s game. He made a difficult catch and gunned down a base runner for a double play in Pittsburgh last week. On Friday, he and Suzuki teamed up to prevent a run.

With Starlin Castro on second base after his second double of the game in the third inning, Anthony Rizzo lined a single to right field. Bernadina fired a one-hop bullet slightly to the right of home plate, but quick and strong enough to give Suzuki time to adjust. He nabbed the ball and dove across the plate to tag out Castro.

Denard Span also flashed his defensive prowess with a diving play in the fifth inning. Samardzija drove a ball to deep center field. Span took his normal direct and smooth route to the ball, gliding over the grass. He reached for the ball at full speed and tumbled onto the warning track. He sat up on the ground, dirt all over his uniform. With the catch, Span prevented a leadoff runner to reach base, which had been a problem for Detwiler.

Detwiler allowed the leadoff hitter to reach base in three of the first four innings, all on doubles. In the first inning, it would lead to a run. In the third, back-to-back doubles to start the inning by Samardzija and Castro tied the score at 2.

Detwiler struggled to keep the ball down in the strike zone. He surrendered eight hits, including six doubles, but allowed only two runs. “Those guys are not going to score if there’s not a hit or a flyball or anything so you have to bear down,” he said.

Detwiler eventually settled in and retired 11 of the last 13 batters he faced. He and Suzuki adjusted to a fastball-hitting Cubs lineup and began using his curveball beginning in the second inning.

“We figured we had to do something to kind of get them off of it a little and maybe get Ross a feel for it a little bit,” Suzuki said. “As the game went on he got better and better.”

After Julio Borbon grounded out for the second out of the sixth inning, Johnson emerged from the dugout to take the ball from Detwiler. Johnson seldom pulls a pitcher mid-inning but he didn’t want Detwiler to face Castro again. He also sat at 90 pitches. And, Johnson said, a well-rested bullpen needed the work.

Craig Stammen, on seven days’ rest, notched the final out of the inning, stranding a runner at third base. He recorded the final seven outs to preserve the win.