BOSTON — Miami pitchers' control problems came on the throw to first.
Losing pitcher Tom Koehler and reliever Sam Dyson each fired wildly for errors, leading to five unearned runs that carried the Boston Red Sox to a 6-3 victory over the Marlins on Wednesday night.
"Just sloppy," Miami manager Dan Jennings said. "It's really uncharacteristic of who we've been. We have to do a better job of taking care of the ball. There's no excuse for that."
Michael Morse hit a solo homer for the Marlins, who lost their fourth straight.
The loss completed a two-game sweep of the interleague series. It was Boston's fourth consecutive series victory, also a season high.
Koehler (7-5) was charged with five runs — one earned — on five hits in six innings.
"They were taking advantage of mistakes," he said.
Catcher J. T. Realmuto also had a throwing error.
Rick Porcello held Miami to two runs in six innings to snap a career-worst, seven-game losing streak, David Ortiz hit a two-run homer and the surging Red Sox won their season-high fourth straight.
Porcello (5-9) gave up eight hits, struck out four and walked one, halting a stretch that included giving up seven runs in two innings in his previous start.
Koji Uehara got the final three outs for his 21st save, collecting one for the third straight game.
The Red Sox capitalized on Koehler's throwing error to take a 4-0 lead with four unearned runs in the third. With a runner on first, Koehler fired Mookie Betts' comebacker wide of first, sending runners to second and third. Boston made it 2-0 on Brock Holt's run-scoring grounder and Xander Bogaerts' RBI single before Ortiz hit his homer into the Green Monster seats.
In the fourth, the Marlins had consecutive RBI singles by Realmuto and Cole Gillespie. Porcello made a nice play on Christian Yelich's grounder, lunging to his right before throwing to first to leave the bases loaded.
Ortiz doubled leading off the sixth and scored on Pablo Sandoval's double-play grounder.
Alejandro De Aza stole third and scored on catcher Realmuto's throwing error. Morse homered over Boston's bullpen.
Marlins: 1B Jeff Baker, who left Tuesday's loss with oblique pain, was out of the lineup. Justin Bour started at first and went 1 for 4.
Red Sox: 2B Dustin Pedroia, on the 15-day DL with a strained right hamstring, is eligible to return for Friday's opener of a series at Fenway Park against the New York Yankees, but manager John Farrell said the club hadn't decided yet. "The work continues to increase, the volume, the intensity — all baseball-related stuff," Farrell said. "Pedey's responded well. He's going to be on the field when he's first ready without any undue risk."
THAT'S FINALLY OVER
Ichiro Suzuki snapped a career-worst, 0-for-29 skid with a bloop single.
INTERLEAGUE ROAD WOES
The Marlins have lost nine straight in AL parks, dating back to last season. They've dropped seven in a row this year.
Marlins: RHP Jose Fernandez (1-0) is scheduled to start the opener of a four-game series Thursday at home against Cincinnati and LHP David Holmberg, who is slated to make his first start of the season.
Red Sox: Off Thursday. RHP Clay Buchholz (7-6) looks to continue a strong run on Friday when Boston hosts the AL East-leading New York Yankees and RHP Michael Pineda (8-5). Buchholz has won his last four starts, posting a 0.87 ERA.