The Cubs were still upset about the call hours after plate umpire Vic Carapazza ejected Ian Happ.

‘‘It’s tough when you do your job, come off the bench there and have a great at-bat,’’ Happ said. ‘‘It’s unfortunate for the team.’’

‘‘The turning point for us was the Happ at-bat,’’ manager Joe Maddon said. ‘‘It’s just frustrating when a guy does what he’s supposed to do.’’

Yes, Nationals right-hander Joe Ross’ full-count pitch with the bases loaded was outside, and Carapazza’s call cost the Cubs a run. But there were other reasons the Cubs lost 7-2 on Saturday. The Nationals put the ball in play when they had to, and the Cubs struggled to make decent contact when they needed some offense.

And that, as much as the bad call in the fourth inning, is what hurt the Cubs, who would have cut their deficit to 5-2 if Happ had walked.

‘‘Give them credit, they moved the baseball,’’ Maddon said. ‘‘That’s the thing we didn’t do. Otherwise, that game would’ve been 5-5 or whatever at some point. They moved the ball when they had to; we did not.’’

Because of that, the Cubs have bigger issues than the reviled uniforms they’re wearing this weekend.

They have dropped back-to-back games to the Nationals, getting outscored 16-5 in the process. And though the Cubs seemed to like how he threw Saturday, left-hander Jose Quintana still gave up five runs (four earned) in four innings and lost for the first time since June 22.

And now the Cubs must face right-hander Stephen Strasburg on Sunday in an effort to avoid a home sweep, something that would be especially costly because of their road problems. After the series finale, the Cubs have a day off before visiting New York for a three-game series against the Mets, who are chasing a National League wild-card spot.

‘‘There’s a couple of things there that went against us, but overall it’s a frustrating game,’’ Maddon said. ‘‘The biggest thing we did wrong today is we didn’t move the baseball when we had to. That’s it.’’

Tony Kemp, who had eight assists and five putouts at second base, saw what the Nationals are doing well.

‘‘[The Nationals] put up good at-bats today,’’ said Kemp, who became the first Cubs second baseman with at least eight assists and five putouts since Ryne Sandberg on July 24, 1992. ‘‘They put the bat on the ball, and good things happen. You have to credit them. They’re doing a lot of things well right now, and tomorrow we have to stop them.’’

Happ and the Cubs had a chance to do something in the fourth. Anthony Rizzo led off with a walk, and Javy Baez followed with a ground-rule double. Kyle Schwarber and Victor Caratini then struck out before Kemp walked to load the bases, bringing Happ to the plate as a pinch hitter for Quintana.

With the crowd of 40,658 on its feet, Happ was called out on strikes, then tossed after a brief argument.

‘‘It was awesome,’’ Maddon said of the at-bat. ‘‘He walked. He absolutely walked. That’s a walk 100 percent of the time.’’

Happ said Carapazza guaranteed the pitch was a strike after the ejection, and Happ wasn’t about to try to foul off a pitch he thought was a ball.

‘‘I made a good decision,’’ Happ said. “I’m not going to try to foul a ball off. I’m trained that way; I’m trained to take balls. I think I’ve proven through my time in the big leagues that I have a pretty good command of the strike zone, that I understand where the pitches are.

‘‘I don’t get very animated unless it’s something I really disagree with.’’