SAN FRANCISCO -- The Padres reinforced one of baseball’s eternal truths Wednesday night, and not in a way they would have preferred.

They demonstrated the thin margin between success and failure by committing three errors, which benefited San Francisco’s offense in its 4-2 decision over the Padres. The Giants swept the two-game mini-series while extending San Diego’s losing streak to four games. On a larger scale, the Padres have dropped 11 of their last 16 games to fall from second place in the National League West.

The Padres mounted a serious ninth-inning threat against Giants closer Will Smith, loading the bases with two outs. But Smith coaxed Manuel Margot’s harmless popup to record his 16th save in as many opportunities.

• Box score

Earlier, the Padres helped the Giants inch ahead. With San Diego clinging to a 2-1 lead in the fifth, Steven Duggar reached second base on an infield hit combined with shortstop Fernando Tatis Jr.’s accompanying throwing error. Duggar scored on a single by Donovan Solano, who advanced to third base on left fielder Josh Naylor’s throwing error. Solano came home on Evan Longoria’s infield single.

Another Padres mistake helped the Giants add a seventh-inning run. Reliever Robbie Erlin fielded Duggar’s weak grounder and uncorked a high, wide throw past first base. Duggar reached second base on the play and scored on Solano’s double.

Padres manager Andy Green defended Tatis and Naylor, calling the rookies “young kids who are both really talented baseball players.” Green categorized the errors as “good effort plays where we just came up short and tried to do a little bit too much.”

Green said that Tatis, a leading Rookie of the Year candidate, “is going to make some really special plays. You have to look at his drive to try something nobody else can do.”

The correct course to take against Duggar, Green pointed out, would have been inaction.

“Duggar can run down the line. There’s no real throw there,” Green said. “Even if he makes a perfect throw, he’s safe. So I think he’ll learn from that. He’s a smart guy.”

Green pointed out that Naylor remains relatively inexperienced in the outfield after spending his first four professional seasons (2015-18) playing primarily first base.

“He’s short on time in the outfield,” Green said. “He’s going to continue to grow out there.”

San Diego’s offense could benefit from some growth. Manny Machado is batting .195 (17-for-87) with one home run and10 RBIs in his last 25 games. Wil Myers is hitting .219 and his 84 strikeouts are the third-most in the National League. After watching starter Joey Lucchesi pitch six strong innings, Green insisted that the offense “[had] to do more offensively tonight ... to help him.”

Performing before a group of relatives and friends from nearby Newark, Lucchesi tried to help himself by collecting his first hit of the season, a second-inning single. It was part of an encouraging night for Lucchesi (5-4), though he absorbed the decision. He felt so good physically that he thought Green would leave him in for the seventh inning.

“I was ready to go,” Lucchesi said.