SAN FRANCISCO -- The scene that unfolded in the Cubs' dugout Friday night was born out of frustration. Willson Contreras slammed his chest protector to the ground. Soon, Anthony Rizzo was arguing with his longtime teammate.

The specifics of what set Rizzo off ahead of the top of the eighth inning of Chicago's 8-5 loss to the Giants were kept in-house in the wake of a second straight defeat. But Rizzo did meet with the media after the game to answer for the heated moment.

"It's just competition and what's at stake and everything," Rizzo said. "The beauty of this team is we know each other and have played with each other for so long that we can have those brotherly love conversations."

There is no secret about what is at stake for the Cubs.

Going into the road trip through San Francisco and San Diego, it was well-documented that the coming weeks were potentially critical to the Cubs' season. The North Siders climbed to the top of the National League Central with a 19-win May and are now being tested with June’s grueling schedule.

After dropping the opener against the Giants on Thursday, starter Jake Arrieta took the mound for the Cubs while feeling ill. The pitcher admitted following his two-inning disaster -- one that included a 42-pitch, 10-batter, six-run second -- that he attempted to pitch through fatigue.

"Apparently, what I had for lunch today made me pretty sick," Arrieta said. "I threw up before the game and then a few times after I came out of the game. I was really weak. I tried to go out there and do what I could. I wasn't able to, unfortunately."

Arrieta understands his importance to a Cubs team trying to push for a postseason berth with an expiring core group. Since logging a 2.57 ERA in his first five turns this season, though, the righty has turned in an 8.28 ERA in his last six outings.

His rough outing rendered the two-run home runs launched by Kris Bryant (first inning) and Joc Pederson (fourth) to box score footnotes, rather than game-changing blasts. The two homers yielded by Cubs rookie reliever Keegan Thompson in the fourth did not help, either.

It was a recipe for frustrations boiling over.

"That's just part of the family atmosphere I think you get in baseball," Cubs manager David Ross said. "Guys are competing at the highest level and trying to continue to fight, do what's best and win. Sometimes you're not going to see eye to eye."

There was nothing in the bottom of the seventh that jumped out as a catalyst for the barking between Rizzo and Contreras when they returned to the visitors' bench. As things started to escalate, Ross stepped in, guiding Rizzo to the opposite end of the dugout.

Rizzo said he and Contreras -- teammates going back to the Cubs' 2016 World Series championship season -- cleared the air.

"It ends there. We just move on," Rizzo said. "With our relationships here, it's just so easy to talk to each other like we're brothers."

Rizzo also took the moment to praise Contreras, who is well-known for playing with a surplus of emotion.

"I love Willson," said the first baseman. "I think the way he plays for this team, for our city -- with the passion he plays with, you can't match it in this league."

Ross did not expect the incident to have any negative impact going forward, either.

"I don't think it's anything that's a huge deal," said the manager, "or something that I'm extremely worried about."

The Cubs need it to end there, too. The road through June and back to October is not going to get any easier.

With Arrieta's outing as the latest example, Chicago still has plenty of things to sort out with its contact-reliant rotation. The pile of players currently on the injured list has put the club's depth to the test. A bullpen that was elite through May has displayed some recent cracks.

All of that said, Pederson has brought an outsider's perspective to a clubhouse full of longtime teammates like Rizzo and Contreras. And the Cubs’ outfielder believes the team does have the makings of a group that can overcome the roster's imperfections in the end.

"I think being on the Dodgers for so long," Pederson said, "you understand that it's not the most talented team that wins the World Series. It kind of is a special group of guys that have a culture and a trust and a special bond that is able to push past some of the individual statistics and get team wins just by having a closer group. I think that we have that."