MIAMI -- Welington Castillo had a banner day at the plate, and all he could think about was his role in a scary injury for a teammate.
Colvin was standing on third base in the second inning when he was struck by a sliver of Castillo's maple bat. Colvin scored on Castillo's double, but was replaced in the field in the bottom half and taken to a hospital.
"I feel really bad about it," Castillo said. "It wasn't on purpose, but he's my teammate. I hope he's getting better."
A Cubs spokesman said Colvin was in stable condition at Jackson Memorial Hospital and is expected to remain there for the next few days for observation.
Colvin was watching Castillo's liner into the left-field corner and looked surprised when he was hit by the bat. He is expected to miss the rest of the season.
"It's scary, that's the danger of a maple bat," Cubs infielder Jeff Baker said. "Thank goodness he's OK."
The Marlins issued 12 walks, tying a franchise record for a nine-inning game set Oct. 5, 2001, against Atlanta. Brett Sinkbeil issued three consecutive bases-loaded walks in Chicago's six-run second.
"Obviously, it was the walks," Marlins manager Edwin Rodriguez said. "You can't defend a walk. That was the frustrating part."
Bobby Scales, Brad Snyder, and Baker each drove in a pair of runs for the Cubs, who completed a three-game sweep and earned a sixth consecutive win for the first time since a seven-game streak from August 23-29, 2008. They also wrapped up an 8-1 trip, the best road trip of at least nine games in franchise history.
The Cubs' starting lineup had four rookies and seven players without a home run this season, but they chased Andrew Miller (1-3) during the second.
"Is that fun or what," Cubs manager Mike Quade said. "You don't sweep without these guys playing well. It's fun to watch. Winning is great, but when you get kids to give you a lift like that, that's huge."
Scales got Chicago off to a nice start with a two-run single in the first and Snyder added another two-run single in the second for his first career hit. Castillo also had the RBI double on the play that sent Colvin to the hospital.
Miller recorded just four outs and was charged with five runs and three hits. He walked four and struck out one.
"It was pretty bad," Miller said. "No command, no stuff, and bad results. I hung the team out to dry, didn't give us a chance to win, killed the bullpen."
Jeff Samardzija (2-1) pitched six innings for Chicago, allowing three runs and three hits. He improved to 2-0 with a 2.31 ERA in two starts since being recalled from Triple-A Iowa.
Castillo's two-run homer off Burke Badenhop in the ninth was the first of his career.
"I knew the guy from Triple-A so I know he has a good two-seamer so I knew I had to get on top of the ball and I cheated a little bit," Castillo said.
Marlins SS Hanley Ramirez missed his third straight game with a sore left elbow. ... Marlins rookie Logan Morrison extended his streak of reaching base safely to 38 games with a walk in the first inning.