CHICAGO -- In his younger days, Cole Hamels might not have been so understanding about his manager making the slow walk to the mound to take the baseball from him in the fourth inning. Hamels not only has the benefit of experience now, but he sees the larger picture and what is at stake.

"Every game right now is a playoff game," Hamels said. "We have to win."

In an 8-2 win over the Reds at Wrigley Field on Monday night, it was clear early on that Hamels was fighting himself more than Cincinnati's lineup. Cubs manager Joe Maddon decided to pull the plug in the fourth, and in doing so turned things over to a bullpen that has evolved into a strength for Chicago. After 5 2/3 shutout relief innings, the North Siders won their fifth straight game.

Man, have times changed.

• Box score

Throughout this season, the Cubs' relief corps has been a constant storyline mostly for all the wrong reasons. There was the lack of a true closer for the first two-plus months and bouts of chaos in the eighth inning, with a list of injuries and other issues sprinkled into the mix. It was hard to envision the group stabilizing like it has over the past several weeks.

So, when Maddon took the ball from Hamels' left hand, there was no questioning the move. This is crunch time, and suddenly the Cubs have a bullpen they trust.

"There was nothing to mess around with there," Maddon said. "This isn't April, May, June baseball. And to Cole's credit, he got it. He's a pro. He understood."

With the win -- one that featured Kyle Schwarber's 37th homer and Nicholas Castellanos' 55th double -- the Cubs remained a game ahead of the Brewers in the race for the National League’s second Wild Card spot. Chicago moved within a half-game of the Nationals for the NL’s top Wild Card seed, while staying two games back of the NL Central-leading Cardinals.

Hamels labored through 73 pitches (firing 36 strikes along the way) in his 3 1/3 innings. The left-hander issued five walks, hit another batter and registered fewer than five innings for the third start in a row. This is the first time in Hamels' long, decorated career that he has had a streak of that kind within the confines of one season.

In the fourth, sidearmer Steve Cishek took over with one out, runners on the corners and the Cubs holding a 3-1 lead. The righty allowed a sacrifice fly (one of two runs on Hamels' line) but escaped further damage with a slider that froze slugger Eugenio Suarez for an inning-ending strikeout.

"It felt good out of the hand, especially since I had just air-mailed one to the backstop," Cishek said with a laugh. "So, I set him up for it, I guess."

Cishek set things up for the rest of the bullpen, too.

Rookie right-handers Alec Mills and Rowan Wick each logged two innings. Lefty Kyle Ryan and righty David Phelps got through the ninth -- the latter escaping a bases-loaded jam -- to finish things off.

"You have to give credit to the bullpen," Hamels said, "to be able to come in and do what they did for that many innings. Those are some stressful innings to fill, and to be able to do it the way they did it is outstanding for us, especially to start a series off."

Monday's showing lowered the Cubs' bullpen ERA to a NL-leading 2.32 for September. That comes after the group had a 4.12 relief ERA on the year entering the final month. Heading into Monday, the 'pen had 11.02 strikeouts per nine innings in September, compared to 8.77 the rest of the year. The strikeout rate was up to 29.2 percent this month (vs. 22.7 percent in the previous five months).

Most of this month's relief work has been done with closer Craig Kimbrel (signed to a blockbuster contract in June) on the injured list due to right elbow inflammation. Brandon Kintzler, who has been one of the team's main setup men all year, has been limited to just 1 2/3 innings in September due to a mild left oblique strain. Pedro Strop, while better of late, has not looked like himself all summer.

The Cubs hoped to have late-inning arm Brandon Morrow this season, but he missed the entire year with arm troubles. Carl Edwards Jr., Mike Montgomery, Brad Brach and Randy Rosario -- all in the Opening Day bullpen for the Cubs -- now pitch for other teams. Free-agent signings like Tony Barnette and Xavier Cedeño did not work out.

“There's a lot of complementary pieces right now,” Maddon said of the revamped relief corps. “But, Rowan Wick has really been like this linchpin to this whole resurgence of the bullpen.”

Besides Wick, Ryan and Cishek, not to mention Tyler Chatwood earning more crucial moments, it has been Chicago's crop of September additions who have played a large role, too. Mills, Brad Wieck, Duane Underwood Jr., James Norwood and Danny Hultzen have combined for a 2.14 ERA in 21 innings on the month.

"When you play for the Cubs' organization, there's high expectations," Cishek said. "I know the guys in the Minor Leagues even feel that. In Spring Training, when they get sent down, they know they have a chance that they're going to make an impact on the team when they get called up. They've done exactly that. They've stepped up big time."