CHICAGO (AP) -- In 89 starts with Oakland, Rich Harden struck out 10 or more batters twice. In eight starts with the Cubs, he's racked up double-digit strikeouts five times.
Talk about a changeup.
Harden matched a career-high with 11 strikeouts on Sunday, Mark DeRosa homered for the fourth straight game and the streaking Chicago Cubs took their eighth straight series with a 6-1 win over the Washington Nationals.
Harden, 4-1 with a 1.47 ERA since his July 8 trade from Oakland, continued to dominate National League hitters.
Where did it come from?
"I don't know," he said. "I think definitely you have to give a lot of credit to [catcher Geovany] Soto. We've been working pretty well together. I'm comfortable with him behind the plate. I think a lot of it is mixing up pitches, keeping them guessing."
Harden relies on his fastball-changeup combination, and can finish with a diving, split-finger fastball or the occasional slider. Whatever he's doing seems to be working. Harden has struck out 21 in 14 innings, with zero walks, in his last two starts.
"When he doesn't get behind in the count and throw a lot of balls it's tough," said Nationals third baseman Ryan Zimmerman, who struck out all three times he faced Harden. "He can throw anywhere from 88 to 91 and kind of sink it. He can come with 95 to 97. It's just tough to pick up. He throws everything from the same arm angle."
Backed by three home runs, Chicago (80-50) moved 30 games over .500, while the Nationals managed just four hits and lost their fifth straight series.
"We really rode the long ball today," Cubs manager Lou Piniella said.
DeRosa became the first Cubs player to homer in four straight games since Fred McGriff did it in September 2001, and outfielder Kosuke Fukudome showed signs of ending his hitting funk when he drove a pinch-hit homer to right in the eighth. He was hitless in his last four games, continuing his second-half swoon that saw his average dip to .262.
Fukudome watched video of himself with Piniella before the game and then went to the batting cages with coach Alan Trammell and hitting coach Gerald Perry.
"He's a good pupil," Piniella said. "We wanted to shorten his stride. It's a simple, little thing, getting his hands set a little quicker, so his swing is shorter, more compact and into the ball."
While Piniella credited the meeting for Fukudome's homer, the veteran Japanese hitter wasn't so sure.
"Lou gave me his point-of-view on what he thought I should change," Fukudome said through a translator. "I was able to work on it a little bit in the cage, but during the game, I can't think of stuff like that while I'm at bat. So I wasn't able to fully introduce what he told me."
The Cubs took a 3-0 lead in the second against Jason Bergmann. DeRosa led off with his 18th homer, Jim Edmonds walked and Soto hit a 3-1 pitch to left for his 19th homer. DeRosa has turned into a run-producing machine, extending career-high marks in homers and RBIs (77). He's hitting .390 with seven homers and 22 RBIs over his last 17 games.
"I can't explain them, to be honest with you," he said of his homer streak. "I'm getting pitches to drive and I'm not missing them."
Nationals outfielder Austin Kearns provided the Nationals' only offense with a solo homer that fell just inside the foul pole in left in the third. Three of the game's first four hits were home runs, an oddity on a day when the wind was blowing in at 10 mph.
Harden struck out the side in the seventh to tie his career-high, which he also accomplished with Oakland earlier this season. He gave up two hits in seven innings.
Bergmann (2-10) gave up four runs, four hits and four walks. He was solid for a while after the Cubs' three-run second, giving up only one hit -- a wind-aided bloop double by Aramis Ramirez in the sixth -- until Mike Fontenot doubled with one out in the seventh.
"After [the second], my curveball took over," Bergmann said. "I just kept throwing it because it was effective."
The slumping Fukudome then came to the plate, hearing some boos thanks to his .145 average in August, and took two balls from Steven Shell before sending his ninth homer to the bleachers in right.
Cubs 1B Derrek Lee sat with upper back spasms after aggravating a lingering injury. Lee said he suffers occasional spasms in his neck and the left side of his upper back, but it rarely causes him to miss time. Daryle Ward started at first base for Lee for only the third time this season. ... Soto tied Randy Hundley for most home runs by a Cubs rookie catcher. ... DeRosa improved his career-high home run total. ... Harden struck out 11 against Philadelphia on June 26.