Hart (0-1) walked five batters, including one intentionally, in five innings one day after he was recalled from Triple-A Iowa to replace the injured Ryan Dempster. Although he worked out of multiple jams and surrendered just one run, he could not match Kenshin Kawakami (5-6), who combined with three relievers to keep the Cubs at bay for the second successive game.
"Baseball is one of those games where sometimes you can go out there and give up five and get a win, and sometimes you can go out there and give up one and get a loss," Hart said. "With the way our offense is [Nos.] 1-9, you know we're going to score some runs. The last two games, we've struggled a little bit doing so, but I know we're going to come back and score 10 at any time."
The Cubs fell to 4-3 on their current 11-game homestand and have scored two runs or fewer in all three losses. Manager Lou Piniella expressed his exasperation with a team that has scored 4.12 runs per game this season, compared to 5.31 in 2008.
"The problem is, you've got to score runs to win, unfortunately," said Piniella, who has grown weary of trying to remedy his team's struggles.
Kawakami had a lot to do with it, as he gave up one run, a sixth-inning homer by his former Chunichi Dragons teammate Kosuke Fukudome. The Cubs put only one serious threat together against Kawakami in his six innings, putting runners on first and second with two outs in the fourth. Milton Bradley grounded out to end the frame.
The 34-year-old rookie from Japan also induced two of Chicago's three double plays to help him get around four hits and two walks.
"He was outstanding," Braves catcher Brian McCann said. "He pitched himself out of an early jam. He dug down deep and really pitched great."
For the second successive game, Cubs hitters explained their minimal production by tipping their caps to the opposing pitcher. On Tuesday, Javier Vazquez allowed one run in seven innings.
Three Atlanta relievers combined to close out the game, giving the Braves' bullpen seven scoreless innings in the series. The best chance the Cubs got in the last three frames came in the eighth against Mike Gonzalez. Koyie Hill, playing for the injured Geovany Soto, hit a leadoff single and moved to second on a sacrifice bunt, before Fukudome smacked a line drive up the middle that shortstop Yunel Escobar snared. Ryan Theriot grounded out to end the inning.
"They always say, 'If you're missing, you keep swinging, you keep shooting, you keep throwing,' whatever," Jake Fox said. "If you're missing it, you keep doing it. I believe that we have enough talent in this locker room, that if they keep doing it, they'll figure it out and we'll get back on track."
The Braves wasted several scoring chances against Hart, who put at least one runner on base in every inning and threw 46 strikes out of 89 pitches. He said he was a little nervous, but benefited from the 33 Major League relief appearances he has made over the past three seasons.
"I pitched behind a little bit today, and the walks didn't help," Hart said. "But I made pitches when I had to, got out of some big jams, and the most important thing, [I] just kept us in the ballgame."
Atlanta did get to Hart in the third. With two outs and nobody on base, Nate McLouth doubled and came home when Martin Prado's single to left went under Fox's glove.
Casey Kotchman added the decisive second run with a homer off Angel Guzman in the sixth. The Cubs' defense also contributed to a pair of Atlanta insurance runs in the ninth, as Prado's single got past a charging Fukudome, allowing McLouth to score from first and Prado to advance to third. Kevin Gregg's wild pitch brought Prado home two batters later.
"Errors happen," Fox said. "As long as you're making aggressive errors and getting after it, you can handle that. It's when you make tentative errors, that's when there's a problem."
The Cubs remained positive heading into a four-game series against the National League Central-leading Cardinals that starts Friday at Wrigley Field.
"It's been a year of adversity, no question about it," first baseman Derrek Lee said. "It's been a grind, but you just keep going about your business. You can't put your head down. You've got to say positive through whatever is going on, and it's going to turn for us."
Andrew Simon is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.