But Dempster (12-9) couldn't. He gave up seven runs over three innings, his shortest outing of the year, and took the loss. It was the right-hander's briefest stint since a 2 1/3-innings start on June 27, 2008, against the White Sox -- when he gave up eight runs on seven hits.
Dempster was unbeaten in August, posting a 4-0 mark and 1.31 ERA in his previous five starts. He's ready to turn the calendar.
"That wasn't a good job, a good performance by me," Dempster said. "We should've won that game. We scored seven runs but it's hard when your starting pitcher, being me, puts us in a hole and it's 7-0. That's a lot to overcome. I didn't execute pitches, didn't get ahead of hitters. No explanation, I just didn't get it done."
The loss was just the third in eight games for Cubs manager Mike Quade, who took over for Lou Piniella on Aug. 23. He'd relished the 14 runs in his home debut on Monday but on Tuesday found himself pulling his starter after three innings.
"You're so used to seeing [Dempster] get through a tough situation like that, and he just couldn't tonight," Quade said. "You just turn the page and look forward to his next start."
Karstens (3-10) picked up the win, his first since June 19. He held the Cubs to two runs, both coming on Koyie Hill's first homer since May 29, 2009, with one on and one out in the fifth. No, Hill didn't get the ball as a souvenir.
"Even some of the guys on the other team were telling me 'Good job,'" Hill said. "I told [Ryan] Doumit, I had one more homer than a dead man -- and I was happy to lead my family in homers, which is saying a lot because I have [a 5-year-old and a 2-year-old] little girls with pretty good hands, so I'll take it."
Apparently, the Pirates wanted revenge after Monday's lopsided loss to the Cubs. Jose Tabata walked with one out in the first, reached third on Walker's single and scored on Jones' groundout. Pedro Alvarez hit an RBI double, Doumit was hit by a pitch, and both scored on Ronny Cedeno's double to make it 4-0.
Dempster actually had a chance to get out of the inning earlier with Jones' potential double-play ball, a comebacker, but he couldn't turn two.
"You've got to put that behind you right away and go out there and make pitches," Dempster said. "I didn't do a very good job making quality pitches tonight. I was prepared and I was ready but I didn't execute. When you don't execute, you get bad results."
Tabata added an RBI triple with one out in the second and Andrew McCutchen made it 7-0 with a two-run single with two outs in the third. At that point, Dempster had thrown 70 pitches. And that was it.
Jones hit his 20th homer in the fourth and Walker launched his eighth into the center-field juniper bushes in the sixth, both off Marcos Mateo.
The Cubs gave the fans who stuck around something to cheer about in a five-run eighth. Starlin Castro hit an RBI single, pinch-hitter Micah Hoffpauir hit an RBI double and scored on Xavier Nady's single, and Alfonso Soriano hit an RBI single to close the gap.
"I'm thrilled they keep playing, but I expect that," Quade said.
So far, the Cubs players have responded well to Quade.
"There's been a lot of communication and a lot of positive things coming out of every game," Dempster said. "Even in our losses and tough times, he's been very supportive and it's been a lot of fun. We've been having a good time playing for him."
"We all respected Lou and everything he brought, and everything he did for the game," said Hill. "But Quade's done a great job. We've always enjoyed being around him. He's a baseball guy first, a personable guy, a good communicator. I think it's been a good transition."
There are now 29 games remaining in what has been a long season.
"The job's still the same," Dempster said. "You come to work and try to do your job the best you can. It doesn't say in your contract, 'I'll try as hard as I can as long as we're in it.' You try as hard as you can every day."