It was the Cubs' third straight loss since they began the sell-off during Monday's 14-4 win over Pittsburgh.
"Not to make excuses. We seem to come out and play every day and play the way we can play. I can only speak for myself. I've got to get that ball down and get some clutch outs when you need them to keep the team in the game. You can sit and make all the excuses you want, but those guys aren't coming back and you've got to work your way around it and figure out what you've got to do to make it work."
Samardzija pitched well in July after a four-game losing streak in June. He entered Friday's start with a 2-1 record and 1.91 earned-run average in five July starts, and looked strong through the first four innings, allowing only two hits, including a solo home run by A.J. Ellis in the third.
But Samardzija gave up a pair of runs in the fifth and a two-run single to Hanley Ramirez in the sixth, ending his night with the Cubs trailing 5-1.
"He didn't have his split today that he's able to get swings and misses with and put guys away with when he had to," manager Dale Sveum said. "A.J. Ellis had a big night. Those home runs kind of changed the game around a little."
Ellis cranked another home run off Manny Corpas in the eighth, giving the Dodgers an insurance run.
But the Cubs offense was so lackluster it wasn't really needed. The Cubs had back-to-back walks in the ninth off reliever Shawn Tolleson, but Darwin Barney grounded into a game-ending double play.
Dodgers' starter Chad Billingsley (7-9) allowed one run on four hits over seven innings for the win.
"They way he pitches inside to the lefties makes it a little tough," Sveum said. "That was about as best command of a fastball and cutter as I've seen him have."
The Cubs are beginning a six-game West Coast swing to Los Angeles and San Diego, having gone 2-1-1 in their last four road series after a 1-9-3 record in their first 13 series away from Wrigley Field.
"A lot happened the last couple days, but you've got to keep your head on straight and go to work," Samardzija said.