Cubs manager David Ross came out of the dugout to argue after Bryce Harper drew a walk. Just about everything unraveled after that, and a once-promising season continued to slip away.

Odúbel Herrera hit a three-run homer, and the Philadelphia Phillies went deep five times while handing the Cubs their 10th straight loss with a 13-3 romp on Monday night.

Andrew Knapp, Didi Gregorius, Rhys Hoskins and Alec Bohm also connected.

The Cubs remained winless since Zach Davies and three relievers combined to no-hit the Dodgers in Los Angeles on June 24. They also extended their worst losing streak since a 12-game slide in May 2012.

The Cubs were tied with Milwaukee for the NL Central lead prior to their tailspin. Now, they are 8 1/2 games behind the first-place Brewers and third in the division.

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"We're obviously trying," Javier Báez said. "It's not fun, let me tell you that. But we're trying and everybody's mad. I'm mad about it. The only thing I can do is come back tomorrow and try it again."

Herrera’s drive against Kohl Stewart capped a six-run eighth that broke open a 4-2 game. Bohm also drew a bases-loaded walk and two more came in when third baseman Eric Sogard misplayed Ronald Torreyes’ grounder.

Knapp led off the third with his second homer, and Gregorius added a solo shot against Davies in the fourth. Hoskins and Bohm went back to back against Sogard in the ninth.

Andrew McCutchen had three hits and scored two runs. He delivered a tiebreaking double in the sixth, and the Phillies scored twice in the inning after Ross got ejected by plate umpire Nic Lentz following a heated argument.

"We've kinda been waiting for everybody to get healthy," Hoskins said. "I think you can just kind of see the depth and the length of the lineup."

ROSS TOSSED

Ross came out of the dugout after Harper led off with a walk on a 3-2 pitch against Rex Brothers (2-2). First base umpire Joe West got between him and Lentz before Ross left the field. The ejection was Ross’ third this season and fourth in two years managing the Cubs.

Ross felt Harper benefited from complaining after a 3-1 pitch was called strike two. He also acknowledged he didn't see a replay of the fastball that was called ball four, and that someone told him it was low and outside.

"I can admit when I was wrong," Ross said.

He also made no apologies for sticking up for his team.

"It's a fine line," he said. "I don't want to be the manager that complains about every strike when you're in a stretch that we're in right now. That's counterproductive as well. But that one in particular, felt like in the moment he kind of swayed with a high-profile player and a borderline pitch."

McCutchen then drove Harper in with a line-drive double to left and scored one out later on Hoskins’ single off Keegan Thompson, making it 4-2.

Matt Moore went four innings, allowing two runs and four hits. Connor Brogdon (5-2) worked a perfect fifth and sixth.

CUBS FALL BELOW .500

The Cubs (42-43) fell below .500 for the first time since they were 19-20 in mid-May. With All-Star Kris Bryant, Anthony Rizzo and Báez in the final seasons of their contracts, Chicago is looking more like a potential seller than buyer prior to the July 30 trade deadline.

"I don't know what to tell you about this trade deadline," said Báez, who smacked his 19th home run and an RBI double. "I'm really not paying attention to it."

Jake Marisnick homered for Chicago, and Davies lasted five innings, allowing two runs and four hits.

TRAINER'S ROOM

Phillies: McCutchen was in the lineup after exiting Sunday's loss to San Diego because of oblique tightness. He left in the ninth inning of that game after fielding Eric Hosmer’s double.

Cubs: RHP Trevor Williams (appendicitis) is scheduled to throw a bullpen Tuesday, and Ross is not sure if he will make another rehab start at Triple-A Iowa. ... LHP Justin Steele (right hamstring strain) and RHP Dillion Maples (strained right triceps) — also on rehab assignments — were also set to throw.

UP NEXT

RHP Jake Arrieta (5-8, 5.57 ERA) tries again to get back on track for Chicago, while Aaron Nola (5-5 4.44 ERA) gets the ball for Philadelphia. Arrieta got tagged in a 15-7 loss at Milwaukee last week after a seven-run first by the Cubs. He is 0-4 with a 7.82 ERA in seven starts since winning at Pittsburgh on May 25. Nola gave up seven runs in a loss to Miami last week.