Which is a bigger concern for the Nationals: Jayson Werth and Stephen Strasburg on the DL or the bullpen struggling yet again? (Post Sports Live/The Washington Post)

A tarp further delayed Anthony Rendon’s return Thursday night, but that was just fine, because this time, his return was not delayed by injury. Rain splashed on white plastic and added 1 hour 51 minutes to the 53 games that a sprained left knee and a strained left oblique had already made him wait. But when the tarp came off and Rendon jogged to the infield, a missing piece of a battered Washington Nationals lineup clicked back into place, playing second and batting second.

Up Rendon came with two men on and two men out in the bottom of the ninth, his Nationals trailing the Chicago Cubs by a run. Back he went, walking to the dugout, bat in his hand, his moment stolen. Cubs catcher David Ross picked pinch-hitter Clint Robinson off first base with Rendon at the plate. The Nationals lost, 2-1.

“That can’t happen. Took the bat out of Anthony’s hands, one of our better hitters, and it’s just on me,” said Robinson afterward, looking despondent, holding his voice steady. “That can’t happen. I really can’t explain it. I really wasn’t trying to go anywhere, I just couldn’t get back fast enough. “

He lost his chance in the ninth, but Rendon had another two innings earlier with two on and two out in the seventh. He struck out swinging. He bounced his bat off the ground, raging.

During an honoring ceremony at the White House, President Obama announced that the San Francisco Giants were partnering with San Francisco State University and Major League Baseball to build a multibillion-dollar junior Giants youth academy with training facilities, classrooms, batting cages and two baseball fields. (AP)

Before that at-bat, Rendon had singled and doubled.

“I felt alright,” Rendon said. “I tried to calm myself down a little bit more than usual. Just tried to relax, tried not to do too much. Keep it simple and try put the barrel on it.”

He nearly keyed a comeback in the sixth, but the Nationals’ offense has been plodding these days. Even a player who finished in the top five of last year’s MVP voting could not rejuvenate it — at least not yet. So the Nationals lost for the sixth time in seven games. And for the ninth time in 10 games, they scored three runs or fewer.

“He’s a great hitter, I think everybody knows that,” right fielder Bryce Harper said. “He’s gonna help us, most definitely.”

The Nationals trailed by two in the sixth when Denard Span singled against Cubs starter Jake Arrieta. Rendon doubled to move him to third, with the projected top-of-the-order pair finally producing as intended. Arrieta hit a batter, which loaded the bases for Harper. He chopped a ball over the mound and appeared to beat it out, but the Nationals had already used their challenge unsuccessfully. Ian Desmond, moved from the No. 2 spot in the order to sixth with Rendon’s return, lined out hard to first base. The Nationals needed one more hit. That scenario happened more than once as a late start turned into a late night.

“(Desmond) squared it up perfectly. Just a guy standing there,” Nationals Manager Matt Williams said. That’s the way the game goes sometimes. We just keep grinding. Keep goin’ at em.”

Rendon played one inning at second base before moving over to third. He won the National League Silver Slugger award there last season but spent his rehab assignment working at second — where Yunel Escobar was supposed to play. When Rendon sprained his left knee in March, Escobar moved from second to third. When Escobar left Thursday’s game after tweaking his right wrist on a checked swing in the first inning, Rendon moved from second back to third.

The shuffling was secondary. Rendon said before Thursday’s game he is comfortable at both positions, “most comfortable with a bat in my hands.” That is where the Nationals need him most right now because Rendon is the kind of work-the-count, contact hitter that can stabilize a lineup. His two hits helped Thursday, but aided by two calls the Nationals felt did not go their way — one they challenged unsuccessfully — Arrieta held the Nationals to one run on six hits in six innings.

After a mechanical adjustment, Nationals starter Gio Gonzalez nearly matched him. The first three Cubs reached against him. Gonzalez walked the fourth, and the Cubs had a lead before making an out. After allowing two runs in the first, catcher Jose Lobaton told Gonzalez he was flying open, leaving pitches flat and over the plate.

Gonzalez corrected the problem. In the second, he struck out the side. He threw seven pitches in a scoreless third. Gonzalez held the Cubs at two through six innings, allowing four hits and striking out six. After the first four batters reached, four reached in the next 5 2/3 innings.

But Gonzalez’s grit went unrewarded because the Nationals’ offense did not produce again, robbed of its final chance by one mistake — made by a player who gets one chance a game to help or hurt the cause. Today, Robinson helped bring Rendon to the plate with a ninth-inning walk. Then he erased it.

“If Anthony would have hit a three-run homer there and we end up winning the game, we’d forget about it quickly because we have another one tomorrow,” Williams said. “We must do the same in this instance, and be ready to play tomorrow.”

Rendon will help an offense in need of a boost. The Nationals are 29-25, and because the Mets won Thursday night, are now second in the National League East for the first time since May 20.