CHICAGO -- Nicholas Castellanos thought he got it. The Cubs outfielder ran up the first-base line in the 10th inning on Sunday, still gripping his bat tightly as the Wrigley Field crowd's roar rose in anticipation of a walk-off home run.

As Nats center fielder Victor Robles slowed near the ivy, there was still a chance that the baseball would cut through the wind and drop into the basket to unleash bedlam at the ballpark. Instead, the ball dropped into Robles' glove and the result was a collective groan as Castellanos hopped in frustration that he fell a few feet short of heroics.

"I missed it by a tiny bit," Castellanos said after the Cubs' 7-5, 11-inning loss to the Nationals.

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Since his arrival to the North Side, Castellanos has been the motor for Chicago's lineup, but the flaws that have followed the offense all season were highlighted in this series sweep at the hands of Washington. The Cubs have remained reliant on home runs, while the Nationals put on a three-day clinic for putting the ball in play.

Cubs manager Joe Maddon has preached since Day 1 of Spring Training that he wants it all when it comes to his lineup. Maddon wants home runs -- and there have been plenty in a season where power records are being shattered around the game -- but the manager also wants a good two-strike approach, hit-and-runs, aggressive baserunning and a multi-faceted offensive approach in general.

Chicago had not been swept at Wrigley in a series of at least three games since September of 2017, but in this weekend set the Nationals showed the Cubs exactly what Maddon has been talking about all season long.

"The thing that I love the most is that they're bearing down with two strikes," Nationals manager Dave Martinez said. "They're not giving in. They're fouling some pitches off. They're putting the ball in play. They're coming up with key hits. They're taking their walks. And all those things matter."

Entering Sunday's game, the Cubs ranked last in the National League in contact rate (73.7 percent), while the Nationals paced the Senior Circuit in that category (79 percent). Chicago ranked last in the NL in swinging-strike rate (12.4 percent), while Washington also led the way in that area (9.5 percent). It is therefore not surprising that the Cubs have also seen the fewest pitches (40.4 percent) in the strike zone.

The Nationals have piled up 104 runs over their past 11 games -- helping them surge four games ahead of the Cubs in the NL Wild Card race -- and plated 23 runs in the sweep of Chicago. Washington stole seven bases in the series and hit 29 singles within a 37-hit attack. That amounts to 78.4 percent singles, with the MLB rate sitting at 61.8 percent through Saturday.

"That team, they're hot -- probably as hot as any team will ever play right now," said Cubs starter Cole Hamels, who allowed two runs over five innings. "They're putting the ball in play. They're finding holes. They're just putting good at-bats together. It's just a lot different than the way that we saw them earlier in the season. But I think they're doing that to every team."

The Nationals scored five of their runs over the past three games via outs (groundouts or sacrifice flies). That is also an area Maddon would like to see his hitters improve upon down the stretch.

"It's something we have to continue to work at, to move the ball, score runs with outs," Maddon said. "If it was second and third, nobody out, the ground ball to second base. You score a run and get the other guy to third base. Scoring runs with outs is an art form that we have to accomplish, too."

The Cubs scored four of their five runs on Sunday via home runs, and that did help the team fight back to a five-all deadlock by the eighth inning. Addison Russell went deep off Stephen Strasburg in the fifth, Victor Caratini belted a solo shot down the right-field line in the seventh and Kyle Schwarber hit a towering, game-tying, two-run homer to the left-field bleachers in the eighth.

Entering Sunday, the Cubs had scored 49.6 percent of their runs via home runs -- the fourth-highest rate in the NL. Schwarber has a team-leading 30 blasts for Chicago, which has 203 homers and is closing in on the franchise's single-season mark of 235 (set in 2004).

That approach can win plenty of games -- it nearly did on Sunday -- but what happens when there is a power outage? The Nationals spent the past three days showing the Cubs how to create runs, and not just sit back waiting for the long ball.

"What [Washington] demonstrated," Maddon said, "is even if you're not hitting home runs on a particular day, you can manufacture runs. ... Incorporating all kinds of methods within your one lineup is definitely the best way to do it. And right now, they are really taking advantage of [hot hitters] at the top with great speed and great contact ability."