WASHINGTON -- Remember back in early May when the Chicago Cubs were on pace to shatter the MLB record for run differential? Not so much anymore. In fact, the way things are going, they might not even end up leading the league. Not with the way the Washington Nationals are playing.

Including Friday’s 5-1 win over the San Francisco Giants, the Nats boast a plus-140 run differential on the season. With the exception of Chicago’s North Siders, that’s by far the best in baseball. As for the Cubs, even though they were at plus-171 heading into their weekend series against the Oakland A’s, they’re trending in the wrong direction.

In fact, since May 1, Washington’s plus-98 differential is five runs better than Chicago’s plus-93. Since June 1, the Nats’ plus-75 is nearly double that of the Cubs (plus-42). All of which is to say, while contenders around the majors are starting to wilt in the dog days of summer (see: Giants, Rangers, Indians), the Nationals have kept right on rolling.

Back in the District after a 6-3 road trip that included stops in San Fran and Cleveland, Dusty Baker’s club picked up right where it left off, dismantling the NL West leaders with a convincing W that took just 2 hours and 26 minutes. There was good pitching (seven innings of two-hit ball from Gio Gonzalez). There was good hitting (homers from Trea Turner and Wilson Ramos, who set a career high with his 17th bomb). There was good fielding (another errorless game for a Nats defense whose 44 miscues are the fewest in baseball). In other words, it was business as usual.

The scary thing is, the Nats have been doing all this without getting substantial contributions from Bryce Harper (hitting .235 on the season) or Ryan Zimmerman, who has struggled when healthy (.678 OPS) and started just six games over the past month due to injury.

“It was overlooked how Bryce looked tonight,” Baker said of his star right fielder, who went 1-for-3 with a sac fly. “He hit the ball hard tonight, and he hit the ball hard to left field. When he starts doing that, that means he's not pulling off the ball. I told him just keep swinging because good times are right around the corner. We have a few guys here we've still got to get going, and then we'll be operating on full cylinders."

In other words, according to Baker, the team that owns the second-best winning percentage (.596) and the second-largest division lead (seven games) in the majors is still a work in progress.

Um, OK.

For what it’s worth, Baker is not the only one in the Nats clubhouse who feels that way.

“Baseball is a very humbling game for individuals and for teams,” said Turner, who has helped ignite Washington’s offense since being called up from Triple-A Syracuse four weeks ago. “We've got to keep that narrow focus that we've had these last 10 games or so and continue to do what we're doing. As soon as you start to think about that, or how good you're doing, that's when it comes back to bite you. We've got to keep pushing and keep on doing what we're doing.”

What they’re doing is pummeling opponents into submission. Over their last four games, the Nats have outscored the opposition 37-9. Since the All-Star break, they’re averaging 5.2 runs per game, most in the NL.

Said Baker: “Our guys are swinging better and feeling good about themselves.”

The fans are feeling good too. Just ask Mark Melancon. Acquired last weekend from Pittsburgh to strengthen Washington’s most glaring weakness and replace Jonathan Papelbon, the All-Star closer entered Friday’s game in the ninth inning -- his first home appearance since the trade -- and received a rousing ovation from the Nats faithful. Even though it wasn’t a save situation, Melancon was pumped up, as indicated by the stadium radar gun that clocked him at 94 miles per hour, a tick or two up from his normal velocity.

“I had goosebumps running in,” said Melancon, who retired San Fran’s 2-3-4 hitters in convincing 1-2-3 fashion. “It was real special.”

Lately in D.C., there has been a lot of that kind of feeling going around.