Dodgers’ Aaron Harang can’t handle Arizona in 7-2 loss

Don Mattingly sensed the Dodgers could encounter trouble Monday night.

They were facing the decidedly mediocre Arizona Diamondbacks, at Dodger Stadium, no less. But they were also only a day removed from completing an emotional three-game sweep of the San Francisco Giants at AT&T; Park.

“It’s an easy day to be flat,” Mattingly said. “This is a little bit of a trap series.”

The manager’s instincts were right. The Dodgers never had a chance, as the Diamondbacks took what appeared to be extended batting practice against Aaron Harang and claimed a 7-2 decision in Hanley Ramirez’s first game in Los Angeles as a home player.

But the day wasn’t an entire loss, as the Dodgers bolstered their overworked bullpen by acquiring right-handed reliever Brandon League from the Seattle Mariners in exchange for Class-A outfielder Leon Landry and double-A reliever Logan Bawcom.

League, 29, was 0-5 with a 3.63 earned-run average in 46 appearances for the Mariners.

He has a reputation as a dependable workhorse, as he made 65 appearances or more in each of his previous three seasons. He made a career-high 70 appearances for the Mariners in 2010 and was an American League All-Star in 2011.

“I’ve seen this guy,” Mattingly said. “He’s dirty.”

General Manager Ned Colletti said League could be used in the seventh, eighth or ninth innings. League saved 37 games for the Mariners last season, but lost his job as closer in May.

League was said to be a trade target of the Giants.

He has less than $1 million remaining on his one-year, $5-million contract and will be eligible for free agency at the end of the season.

The Dodgers added about $38 million in payroll commitments last week when they acquired Ramirez and Randy Choate from the Miami Marlins.

The Dodgers figure to remain active leading up to the non-waiver trade deadline at 1 p.m. on Tuesday. They remained in contact with the Chicago Cubs about a potential trade for starting pitcher Ryan Dempster, according to people familiar with the situation who spoke on the condition of anonymity because of the sensitive nature of the talks.

They have explored a possible deal that would land them both Dempster and former All-Star outfielder Alfonso Soriano, one of the people said.

Soriano, 36, is in the sixth season of an eight-year, $136-million contract. He is getting paid $18 million this year, as well as the next two years.

The Dodgers’ primary problem Monday was pitching.

Of the nine hits Harang gave up over five innings, all seven of the Diamondbacks runs came on two hits, both home runs.

Harang served up a three-run home run to Paul Goldschmidt in the first inning and a grand slam to Chris Johnson in the fifth inning, dropping the Dodgers into a 7-0 hole.

Harang was replaced by pinch-hitter Bobby Abreu in the fifth inning.

The Dodgers’ offense was slow to start.

They had men on first and second with no outs in the first inning, only for Matt Kemp to strike out and Andre Ethier to ground into a double play.

Another threat was ended by another doubleplay three innings later, when Juan Rivera grounded into one with two on and one out.

The Dodgers finally forced in a run in the sixth inning, when Kemp and Ethier started the inning with consecutive singles. Two groundouts later, Kemp scored, closing the gap to 7-1.

The Dodgers added another run in the eighth inning when Kemp doubled in Rivera.

dylan.hernandez@latimes.com