BOSTON — Bryce Harper favors action over stagnancy, the inclination of youth, and by late Sunday afternoon he could wait no longer. He had blown bubbles and watched for six innings, a foreign experience after 37 games in the major leagues. He marched down the tunnel and straight toward Manager Davey Johnson and told him he was fine. He then repeated himself: I’m fine.

“He made that point very clear,” Johnson said.

When they want something known, these Washington Nationals are unmistakable. Johnson inserted Harper two innings later, after the Nationals and Boston Red Sox had played to a draw for eight innings. In minutes, the 19-year-old flash of energy decided the outcome. Harper dashed around the bases on Roger Bernadina’s game-winning, two-out double in the ninth inning, giving the Nationals a 4-3 victory at Fenway Park to cap a resounding weekend.

The Nationals had swept the Red Sox, another statement for the emergent team with the second-best record in baseball. At 35-23, the Nationals stand 12 games over .500, their highest mark since July 23, 2005, and on a 97-win pace. They have widened their lead in the National League East to two games over second-place Atlanta and a staggering eight over last-place Philadelphia, the five-time reigning division champ. And they did at one of the most venerated parks, against of one the most high-profile teams.

“I know we’ve shown the baseball world what kind of team we are,” closer Tyler Clippard said. “This was kind of a statement series for us in doing that. They’re definitely a good club, and I think we’re better. I think we’re a lot better. We feel really good with what we’ve got going on right now.”

In another corner of the Nationals’ clubhouse, the statement-sweep notion did not sit well with second baseman Danny Espinosa. For him, their record means they don’t need to measure themselves against anyone; their opposition must measure themselves against the Nationals.

“I think we were the team to beat right here,” Espinosa said. “We’re the first-place team.”

The halcyon opening third of the Nationals’ season deepened the chasm between their present and past. The Nationals last came in here in 2006. They sent Livan Hernandez, Tony Armas and Shawn Hill to the mound, and the Red Sox outscored them by 17 runs. This weekend, they swept behind Stephen Strasburg, Gio Gonzalez and Jordan Zimmermann, who Sunday allowed three runs and struck out seven over seven innings. They are not what they used to be.

“There’s a lot of places I felt embarrassed,” said third baseman Ryan Zimmerman, the lone holdover from that team. “Not just here. That’s just the way it was. Now it’s a different story. We’ve got a long ways to go, still. I think a lot of things have changed.”

The Nationals won Sunday despite their No. 2 through 5 hitters going a combined 0 for 15 with a walk and six strikeouts. They overcame the void with two doubles from Espinosa, who gave the Nationals a 3-2, seventh-inning lead in the seventh inning with a two-run double off the Green Monster. Clippard converted his toughest save yet, holding a one-run lead in the ninth by striking out Dustin Pedroia to end the game after allowing a one-out walk.