Alfonso Soriano, Darwin Barney and Lou Montanez each had two hits for Chicago, which kicked off a nine-game homestand with its 11th victory in its past 12 games against NL East teams. Montanez started in right field hours after he was promoted from Triple-A Iowa when the Cubs put right-hander Matt Garza on the 15-day disabled list with elbow stiffness.
The Mets dropped their first game since a pair of magazine articles about owner Fred Wilpon. Wilpon first made a couple of chilly comments about three of the team's biggest stars in an interview with The New Yorker, then told Sports Illustrated the club is "bleeding cash" and could lose up to $70 million this year.
Manager Terry Collins held a pregame meeting and urged his team to focus on its play on the field. The Mets all said they got the message, but it was hard to tell on an unseasonably cool night in Chicago.
Backup catcher Ronny Paulino made two errors, leading to five unearned runs. Pat Misch issued consecutive walks to force in a run and give the Cubs an 8-1 lead. Fernando Martinez booted Reed Johnson's single in the seventh for New York's third error, setting a season high.
Cubs manager Mike Quade had starting pitcher Carlos Zambrano hit for Dempster in the seventh and he delivered a two-run single into center field.
New York (22-25) has dropped three straight after winning three in a row. It also lost left fielder Jason Bay to a stiff right calf in the seventh inning.
Dempster (3-4) allowed one run and seven hits, improving to 10-5 in 26 career appearances against the Mets. He struck out five and walked one.
Dempster got all the support he needed in the second inning. Montanez's one-out RBI double off Jonathon Niese (3-5) put runners on second and third for Koyie Hill, who hit a bouncer to first. Daniel Murphy threw home but Paulino dropped it, allowing Soriano to score.
Barney singled in Montanez and Castro added a two-run single that extended the lead to 5-0.
Paulino also made a throwing error while trying to pick Dempster off first in the sixth, allowing Hill to score from second.
Niese gave up six runs, two earned, and seven hits in five innings. He had won his previous two starts.
Jose Reyes had two hits and drove in a run one day after he was one of three players panned by Wilpon in an article posted on The New Yorker website. Wilpon said the oft-injured Reyes has "had everything wrong with him." He also said outfielder Carlos Beltran was "65 to 70 percent of what he was" and third baseman David Wright was "A really good kid. A very good player. Not a superstar."
NOTES: Cubs C Geovany Soto (left groin strain) is scheduled to play in an extended spring training game in Arizona on Wednesday, then make two rehab appearances with Double-A Tennessee. He could be back in Chicago this weekend. ... Mets OF Angel Pagan (strained left oblique) went 1 for 3 and walked twice in a rehab game with Class A St. Lucie. He is expected to play for St. Lucie again on Wednesday, then make an appearance with Triple-A Buffalo on Thursday. ... Cubs OF Marlon Byrd, who was hit in the face by a fastball Saturday against Boston, saw a specialist at Northwestern and general manager Jim Hendry said the bruising in his left eye had subsided a bit. ... The gametime temperature was 45 degrees.
Jay Cohen can be reached at http://twitter.com/jcohenap