With Jason Hammel limiting the Braves to one hit on Saturday, they have been shut out in back-to-back games for the first time since May 2009, against the Brewers.
"A lot of guys in here are frustrated right now," Chipper Jones said in a quiet Braves clubhouse.
A homestand that started with two victories over Toronto ended with a 3-6 record. The Blue Jays and Yankees each overcame four-run deficits in wins, then the Orioles handcuffed the Braves in consecutive games.
"We're playing good defense and getting some good pitching," Jones said, "but we're not swinging the bats. It's tough sledding right now."
The schedule doesn't get any easier, either. The Braves continue their march through the American League East with three games in New York beginning on Monday, then three in Boston.
"We knew this was going to be tough," catcher David Ross said. "The AL East is good, and we're missing guys."
The lingering injury to Freddie Freeman's left index finger has cost the Braves one of their better hitters, and the pitching staff is also shorthanded.
Delgado (4-7) lost despite giving up just three hits and striking out six in eight innings. He allowed only two runners past second base, but both of them scored.
Meanwhile, Chen (7-2) blanked the Braves on six hits through seven innings, striking out two and walking one in lowering his ERA to 3.36.
Delgado retired 15 of the first 16 batters he faced, but a leadoff double by Adam Jones in the second inning helped the Orioles gain a one-run lead. Jones moved to third base on Wilson Betemit's groundout and scored on Mark Reynolds' sacrifice fly.
The Braves, meanwhile, had four hits in the first three innings but came up empty thanks to a double play in each frame, as Chen induced grounders just when he needed them most.
"Chen wiggled out of some situations," manager Fredi Gonzalez said.
The Orioles then took advantage of two Braves miscues to make it 2-0 in the sixth inning. Left fielder Matt Diaz misjudged Steve Pearce's line drive, which went over his head for a leadoff double. Pearce then was sacrificed to third base by Chen and scored when Delgado committed a balk.
"I feel bad," Delgado said. "I didn't want to do it, but I did. I have to step off. It cost us a run."
Delgado, who lowered his ERA to 4.12 with this effort, walked six over five innings in a 3-0 loss to the Yankees on Monday but had no control issues this time. He walked just one and threw 69 of his 102 pitches for strikes.
"He pitched really well," Ross said. "It's a shame. I feel bad for Randall that he didn't get a win."
It was just the 20th career start for Delgado, who went in with a 5-7 record and 3.82 ERA. The eight innings matched his longest previous start, against Philadelphia on May 3.
"A tremendous outing," Gonzalez said. "I think we took a big step forward with him. ... He was terrific."
The continued strong play of rookie shortstop Andrelton Simmons was also an encouraging sign. Simmons had two of the Braves' seven hits, raising his average to .333, and made the defensive play of the game, making a diving stop to his right and throwing out Jones to end the fourth inning.
"We made some unbelievable plays defensively, and Simmons at shortstop is a highlight reel by himself," Gonzalez said. "I've never seen a shortstop make a play like that, not live, anyway."
Chad Durbin recorded two outs in the ninth for his 18th straight scoreless appearance, and Eric O'Flaherty, who hadn't pitched since June 8 because of a tender elbow, retired the only batter he faced to keep it a two-run game.
But the way the Braves were swinging, that was too big of a deficit to overcome.
"Hopefully, in [the upcoming] road trip, we'll get the lineup going again," said Gonzalez, who expects Freeman to be ready on Tuesday. "We played well against the Yankees here and had nothing to show for it. We need to get our bats going and take two out of three up there."