CHICAGO -- Perhaps the most surprising part of the Chicago Cubs' fast start is that they are leading the National League in stolen bases after five on Tuesday night.
So far they have 25, while last season they ranked 24th in the majors with 65 total.
"A big part of that is want to," manager Joe Maddon said. "There's a lot of want to in stealing bases. There's that cavalier attitude that's necessary where you're not afraid to make a mistake."
The Cubs certainly haven't been making many mistakes of late.
"I love two-out runs, man," Maddon said. "They really hurt the other side badly. When you get 'em, there's nothing more glorious than that. A big part of that is we are grinding out every moment of every at-bat."
Wood (2-1) extended his solid start to the season by allowing two runs and five hits. He lowered his ERA to 3.04.
Starling Marte accounted for Pittsburgh's offense with a two-run homer in the fourth.
Pirates starter Jeff Locke (2-1) took the loss after giving up six runs, five earned, and eight hits in 3 2/3 innings.
"They're just aggressive," Locke said of the Cubs. "You've got to be able to make pitches. That's just what it comes down to."
The Cubs jumped on top with three runs in the second. Russell drove in the first one with a double, and Fowler followed with a two-run single.
Chicago added an unearned run in the third. With two outs and none on, Castro reached on a throwing error by third baseman Josh Harrison and scored on a double by Lake to make it 4-0.
After Marte's drive to left field, the Cubs got the runs right back in the bottom of the fourth on run-scoring singles by Bryant and Castro. They also pulled off a pair of double steals in the fourth, marking the first time they've had four stolen bases in one inning since the first inning against the Montreal Expos on Aug. 23, 1997. It was just the third time overall Chicago had four steals in an inning.
"That's one of the things we've talked about since spring training," Castro said. "They give the confidence to be aggressive. If you're out, you're out. Nobody's going to say something to you."
For Maddon, it's been the Cubs all-around play that has him pleased.
"We're playing at a really high level mentally right now," the manager said. "A lot of energy, trying to make things happen."
Pirates: OF Gregory Polanco (tight left groin) was out of the starting lineup. Manager Clint Hurdle said Polanco was showing some "minimal improvement," and he pinch hit in the eighth. ... RHP Charlie Morton (right hip) threw around 75 pitches Monday at extended spring training and is scheduled to work seven innings in a rehab assignment Saturday with Class A Bradenton.
Cubs: RHP Hector Rondon has been bothered by a sore foot of late, but manager Joe Maddon said his closer was fine after not being used on Monday. . OF Chris Denorfia, who began the season on the disabled list with a left hamstring injury, was held out of the lineup to rest. "Denorfia's still not 100 percent with his leg, so I don't want to push him right now," Maddon said.
Pirates: RHP Gerrit Cole (3-0), who pitches the finale of the three-game series Wednesday night, is coming off a strong effort against Arizona. He is 5-0 with a 3.48 ERA in five career starts against the Cubs.
Cubs: RHP Kyle Hendricks is still looking for his first win of the season. His first three starts were in day games, so this will be his first outing under the lights.
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