CHICAGO -- When the Cubs' dugout was loud and rowdy seemingly with every pitch on Opening Day, it was easy to think it was just excitement over the return of baseball. Nearly two weeks in, Chicago's players have not calmed down.

In a 5-4 win over the Royals on Tuesday night at Wrigley Field, they were at it again, howling over the artificial crowd noise as Jason Heyward sent a second-inning pitch into the North Side night and crashing to the bleacher seats for his first home run of the season. And know that the players believe their self-generated energy has helped fuel the Cubs' 9-2 start.

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"I think it's a huge role," Heyward said. "We know it's a shorter season, but it's going to be a long year. It's going to be a grind, and every game counts. So, we just want to make sure that we're in it every pitch as best as possible, that we're together and that we all feel the love."

Here are three more reasons behind Chicago's strong start:

1. Rotation, defense rolling
Kyle Hendricks admittedly felt off in the first couple of frames against Kansas City, but he credited an in-game chat with catcher Willson Contreras for getting his mechanics in order. That paved the way for a solid seven-inning performance that continued the early dominance of Chicago's starting staff.

"It's been awesome," said Hendricks, who gave up two runs, struck out three and walked none. "Guys, they've been throwing the ball great, honestly. They've been going pitch to pitch, just coming right at guys, being aggressive. So, I'm trying to fall in line with that. We're just trying to keep the ball rolling."

With Hendricks' showing, the Cubs' rotation improved to 8-2 with a 2.01 ERA on the season. In 67 combined innings, Hendricks, Yu Darvish, Tyler Chatwood, Jon Lester and Alec Mills have held opposing batters to a .168 average with 58 strikeouts and 40 hits allowed.

Cubs pitchers have also had stellar defense behind them. Entering Tuesday, Chicago had a Major League-leading 15 defensive runs saved, per Fangraphs. While the sample size is extremely small, the early showing -- including a slick, game-ending pick by third baseman Kris Bryant -- has been reminiscent of the 2016 Cubs.

"That's certainly what it feels like right now," Hendricks said. "It's hard to make comparisons, but yeah, I know we played such good defense that season. I know this is way different, obviously, but just to start, guys are making the pitches, and right behind that, guys are in the game, on their toes and making every play."

2. Overcoming bullpen issues
One of the more amazing aspects of the Cubs' solid start has been rattling off nine wins in 11 games, while enduring a slew of bullpen woes.

Chicago entered Tuesday with a Major League-high 7.55 bullpen ERA, and that was before struggling closer Craig Kimbrel allowed two more runs in the ninth inning. Setup men Jeremy Jeffress and Rowan Wick have been among the arms to help pick up the slack -- and Kyle Ryan entered after Kimbrel's departure Tuesday, getting the final two outs for his first career save.

"I continue to say it to you guys," manager David Ross said. "We really need Craig Kimbrel to be a big part of this bullpen. We have to throw him. We have to get him innings and continue to kind of judge where he's at according to seeing what the hitters do."

Beyond Kimbrel's mechanical issues, the Cubs have also had two relievers wind up on the injured list (Brad Wieck and James Norwood). The group as a whole has labored to find the strike zone, as evidenced by the 15.8 percent walk rate, entering Tuesday.

Still, the Cubs have kept piling up wins.

"I think it talks about the depth that we have with the veteran guys down there," Ross said. "I continue to try to put them in the best situation, and we've talked a lot about poise in the moment. These guys are continuing to step up in these moments."

3. Bottom of lineup production
In the fourth inning, Jason Kipnis yanked a pitch from righty Brady Singer to deep right field, where the ball reached the bleachers for a two-run homer. That was the latest offensive blow from the bottom third of the lineup, which has been critical for the Cubs out of the gates.

"It's been fun," Kipnis said, "because it's been a lot of guys, different guys, that have been active in the wins so far. It hasn't just been one guy taking over, it hasn't just been one guy getting hot. I think you're seeing a lot of guys contribute."

Per Fangraphs, the seven-eight-nine spots in the Cubs' order had produced a .270/.357/.460 slash line with a 127 wRC+ going into Tuesday's game. And then, that section of the lineup went 3-for-8 with Kipnis' homer, plus a double and three walks.

In Tuesday's win, Heyward and Contreras also delivered, with the latter launching a decisive solo homer in the eighth.

"I've been saying for a little while," Ross said, "we get a couple of these other guys going and this is going to be a really potent offense. I think the thing we've talked about numerous times is it's a different guy every night. It felt like that again tonight."