"It's incredible, isn't it?" he said. "If that game is played on another day with the wind blowing in, it's probably a one-run game. ... The ballpark turned around today and our guys took advantage of it."
The Cubs slammed three home runs in an inning for the first time since 2008 en route to a second straight series sweep.
Cubs left fielder Kyle Schwarber went 3-for-4 with two home runs and four RBIs, and had one of the three homers during a pivotal four-run fifth inning.
Center fielder Dexter Fowler and first baseman Anthony Rizzo also homered in the fifth.
The victory was the seventh straight and 13th in 14 games for Chicago (65-48) and temporarily moved the Cubs within one game of Pittsburgh for the National League's top wild-card spot.
Cubs left hander Jon Lester (8-8) worked six innings for his third victory in his last four starts. He allowed two runs, seven hits and two walks and struck out 10.
It was Lester's fourth double-digit strikeout performance of the year and 24th of his career.
"Jonny was outstanding again," Maddon said. "He had to battle through some moments, but he was really good. (Cubs catcher) David Ross does a really good job controlling all of that. Look at his trips to the mound and look at him throwing out runners."
Brewers starter Tyler Cravy (0-4) gave up four runs, four hits and three walks in 4 1/3 innings as Milwaukee (48-68) dropped its third straight and fifth in the last six games.
"He's getting outs, but he struggled the last two times," Brewers manager Craig Counsell said. "It's kind of been that third time through (the order) that feels like it shifted a little bit with the hitters taking better swings against him."
Chicago swept four games from San Francisco last week and completed the three-game sweep of Milwaukee on Thursday.
The Cubs opened the scoring in the second when Rizzo came home on right fielder Jorge Soler's single to left.
The Brewers tied it in the top of the third as right fielder Ryan Braun reached base on an infield single with two outs to drive in shortstop Jean Segura. Braun then stole second and third but was stranded when first baseman Jason Rogers flied out to right.
Milwaukee missed an opportunity to add on in the fifth when Segura doubled and then was caught trying to steal third on a throw from Ross to third baseman Kris Bryant. Segura likely would have scored when Braun later singled to right.
The Cubs instead jumped ahead in the bottom of the inning when Fowler homered to right for a 3-1 lead.
The ball hit the edge of the bleacher wall, ricocheted over the edge of the outfield basket and landed back onto the field. It was initially ruled a double, but replay officials changed it to a two-run homer that also brought in shortstop Addison Russell.
Schwarber then launched a 2-2 pitch to center field for his seventh home run of the season and a 4-1 Cubs lead. That was it for Cravy, who threw 96 pitches.
"I kept playing a lot of things I would have done different, probably, with pitch selections," Cravy said.
Rizzo greeted Brewers right-handed reliever Corey Kneel with a two-out homer to left center for a 5-1 lead.
Rizzo's homer, a team-leading 22nd of the season, came on a 2-2 pitch and marked the first time the Cubs had three home runs in an inning at Wrigley Field since June 21, 2008, against the Chicago White Sox.
Milwaukee got one run back in the sixth as third baseman Hernan Perez singled with one out to deep center to score second baseman Elian Herrera.
Schwarber's RBI single brought home Fowler to make it 9-2.
"It's definitely enjoyable," Schwarber said of the multi-homer day. "(But) it's Wrigley Field, you never know what you're going to get."
NOTES: The Brewers and Cubs will meet in two more series this season, including a three-game set that begins Sept. 21 at Wrigley Field. ... After clubbing his 20th home run of the season and 250th of his career on Wednesday, Milwaukee RF Ryan Braun looks to add to his stolen base total (now at 16) and post the fourth 20/20 season of his career. ... The Brewers will return home Friday for a three-game series with the Philadelphia Phillies, part of a six-game home stand. On Friday, Philadelphia will send LHP Adam Morgan (3-3, 4.06 ERA) against Milwaukee RHP Wily Peralta (2-7, 4.48). ... Cubs manager Joe Maddon envisions either Kyle Schwarber or Miguel Montero as the designated hitter for at least the first of three games against the cross-town rival White Sox starting Friday at U.S. Cellular Field. The White Sox took two of three last month at Wrigley Field. ... The last time the Cubs were this far above .500 was at the end of the 2008 season with a 97-64 record.