Tuesday night, his performance against the lone batter he faced was the difference in a redemptive victory.
The surprising Pirates missed a chance to win 10 in a row for the first time since 2004, but the NL Central leaders still have the major leagues' best record at 51-31.
"There's no guarantee, obviously, you're going to win every game when you're up here," said Pirates manager Clint Hurdle. "You never like to lose, but we weren't able to meet some of the demands that were there for us tonight to get some runs."
Pittsburgh managed six baserunners over the 2 1/3 innings immediately after chasing Pettibone, but did not score. The sequence was punctuated by De Fratus striking out Jordy Mercer swinging with the bases loaded and two outs in the eighth.
"That feeling at the end of that inning, that's why us relievers play baseball," said De Fratus, who has his ERA balloon from 1.46 to 4.70 over a two-week late-June span. "That's the feeling you chase. The only way you get that feeling is getting out of the jam. Every time you feel it, it's just an amazing feeling and you want to feel it as much as possible."
Phillies slugger Ryan Howard ended an 0-for-22 slump (12 strikeouts) with an RBI single in a three-run sixth to open the game's scoring. Howard and Michael Young each had two hits for Philadelphia, which scored all of its runs against Pirates rookie spot starter Brandon Cumpton.
Pettibone (4-3) won for the first time since May 14, a span of nine starts, by limiting Pittsburgh's offense to Garrett Jones' homer in the sixth. In 5 2/3 innings, Pettibone gave up three hits.
"He was good, but it was hot and he kind of ran out of steam," Philadelphia manager Charlie Manuel said. "He did his job and stuff like that."
The rookie right-hander was lifted after Jones' shot, his eighth of the season. Philadelphia's much-maligned bullpen repeatedly worked around trouble for 3 1/3 scoreless innings to finish off the Phillies' second win over their past five games.
Jake Diekman got the final out of the sixth and Phillippe Aumont survived four well-hit balls to pitch a scoreless seventh. J.R. Ramirez, Antonio Bastardo and De Fratus worked around two walks and a single in the eighth. Jonathan Papelbon improved to 16 for 20 in save situations with a perfect ninth.
But little else during the victory came easy for the Phillies, who began the day 9 1-2 games back in the National League East. Philadelphia relievers entered Tuesday with the worst ERA in the NL, and De Fratus said he fed off of that when taking the mound with the game on the line.
"I'm thinking, `I've been failing enough; let's try something different," he said with a laugh. "All kidding aside, here's a chance to redeem yourself, get it done. I've failed before -- it's not like I died from it. Just go back out there, throw the ball hard and get people out."
Cumpton (0-1) got the ball because Jeff Locke was forced to warm up in the bullpen during the 14th inning Sunday. Cumpton was charged with three runs on six hits and a walk with three strikeouts in 5 2/3 innings.
"He continues to come in and throw strikes and be aggressive," Hurdle said. "Other than (two at-bats that ran up his pitch count), it was quick, it was efficient and it was sharp through five."
For the second time in three major-league starts, though, Cumpton ran into trouble during the sixth after a solid five innings. He allowed more baserunners in getting two outs in the sixth than he did through all of the first five innings.
"I got in a groove early on -- the third time through the lineup is definitely a lot tougher," said Cumpton, 4-6 with a 4.16 ERA in 14 games in Triple-A and Double-A this season. "I fell behind a little bit and left some pitches up. I didn't make my pitches and they put them in play and made me pay."
"It's one of those things that when you go through stretches you're just thinking of trying to get hits," Howard said. "You're trying to put in the extra work and everything you can, but it's really a matter of finding real estate."
The Philadelphia runs were the first earned runs allowed by Pittsburgh pitchers over a span of 22 1/3 innings. Before the sixth inning Tuesday, the Pirates had allowed one earned run over the previous 36 innings.
The Pirates optioned INF Josh Harrison to Triple-A Indianapolis to make roster room for Cumpton. ... Pittsburgh had won 10 of its 11 previous games started by fill-in starters Cumpton, RHP Jeanmar Gomez and RHP Phil Irwin. ... Locke will start Wednesday's game, RHP Gerrit Cole starts Thursday and Gomez will return to the bullpen for the Pirates. ... Pittsburgh RHP A.J. Burnett, on the disabled list since June 13 because of a right calf strain, threw a simulated game Tuesday. ... Phillies RHP Kyle Kendrick will make his next scheduled start Saturday at home against the Atlanta Braves. Kendrick was evaluated Tuesday in Pittsburgh and cleared two days after sustaining a concussion after being hit in the head with a pitch. ... Locke allowed two hits over six shutout innings of a 2-0 win at Philadelphia on April 23. LHP John Lannan, who starts Wednesday for the Phillies, is 1-4 in his career against the Pirates.