Koehler, who threw seven shutout innings against the Dodgers on May 2 in a win at Marlins Park, endured his worst outing of the season, giving up four runs on six hits with five walks in a season-low 3 2/3 innings on 103 pitches.
Miami has now dropped four straight and is 1-4 on the road trip. During the losing streak, Marlins starters have an 8.15 ERA in 17 2/3 innings. None has gone past five innings.
"That's really four in a row for us where we haven't had a starter get past the fifth inning," manager Mike Redmond said. "That's tough to win ballgames, whether we're at home or on the road."
Miami boasts a young, talented staff. When they struggle, sometimes it is the inexperience showing.
"I think it just shows our youth," Redmond said. "We're young up there on the mound. Guys are going to go through times like this, where we struggle with our command and being able to pound the strike zone. Did I think it would be four guys in a row? Absolutely not.
"We've got to make some adjustments. We've got to get back in the zone. These guys have got great arms, and they have the ability to pitch. We've seen it a lot. It's like anything -- when you're going good, guys start to feed off each other. Sometimes that can work the opposite. Sometimes when guys struggle, the next guy feels like he has to do more. Then you've got a snowball effect, which is about where we are now. Somebody needs to step up."
The Marlins' offense gave Koehler some early support, with Christian Yelich belting a home run and Giancarlo Stanton driving in two runs. But the pitching was wild, combining for 10 walks, and given the lead, Dodgers starter Dan Haren settled in and worked seven innings.
"Very disappointing," Koehler said. "I really struggled with command of breaking pitches. I threw some good fastballs, but when you're not throwing breaking pitches for strikes, they're able to eliminate it, and in situations like that, they're able to sit on the fastball and you hang a breaking ball to a guy [Puig] who swings [at the] first pitch and he crushes it. It's a crushing blow in the game."
Miami chipped back to make a game in the eighth thanks to Reed Johnson's two-run homer off Brian Wilson. It was the first pinch-hit homer of the season for Miami, and the sixth of Johnson's career.
It was a tough day all around for the Marlins, who before the game announced that ace Jose Fernandez had been placed on the disabled list with a sprained right elbow.
"It would have been, I guess, a better day if we had won," Redmond said. "Believe me, it's tough. I haven't slept much, and it's a big blow. But we've got to move on. Like I said, these games keep going. We need somebody to step up and give us a good start."
With Fernandez out, the rest of the rotation is being counted on to produce. They have in the past, but the starters have been in a rut of late.
"You can't replace a guy like that," Koehler said of Fernandez. "It's just not doable. Hopefully, he's not out too long. At the same time, I don't think we need to change what we're doing. Obviously, today's not acceptable. We need to get back to what's been going on for a majority of the year."
Koehler, who carried a 1.99 ERA into the game, had a 16-inning scoreless streak snapped.
The Dodgers did real damage with two outs in the fourth inning. With the Marlins leading, 3-1, Koehler walked Drew Butera and Dee Gordon. Puig, who finished with four RBIs, put Los Angeles in the lead for good with a three-run homer.
"I thought we all did good tonight," Dodgers manager Don Mattingly said of his offense. "[When Koehler opposed us] in Miami, [he] had good stuff, and we didn't do a lot with him. Tonight we made him throw strikes, the guys got on base. We were patient with him, and Yasiel's home run was huge. We did a nice job with him as a team."
Stanton drove in two runs and extended his career-best hitting streak to 14 games.
Now with four home runs, Yelich has matched the total of his 2013 rookie season.
For the second straight game, Yelich connected on a home run. The 22-year-old from Thousand Oaks, Calif., grew up roughly 40 minutes away from Dodger Stadium. Before he was the Marlins' first-round pick in the 2010 First-Year Player Draft, he worked out for the Dodgers at their storied ballpark, but he never played there in a Major League game until Monday.
His home runs in each of the past two days came with his mother in attendance.
In addition, he led off the game with a single and scored on Stanton's groundout.
For the Marlins to get back on a winning track, they will be banking on their starters. And to have four straight disappointing starts is baffling to a team that is still one game above .500.
"It's a little weird," Koehler said. "But now we've all had them. Now it's time to step up and show what we're all capable of. It's a long season. You're going to have good games, and you're going to have bad games. But the key is pitching to keep your team in the ballgame. Today I didn't do that."