CHICAGO -- Cubs manager Joe Maddon felt it was time to let rookie catcher Willson Contreras take Jake Arrieta out for a "test drive."
On Thursday, for the first time this season, Contreras was behind the plate to catch Arrieta in the Cubs' series finale against the Brewers, a 9-6 win that capped a four-game sweep for Chicago. Miguel Montero has been matched with the reigning National League Cy Young Award winner this season, although David Ross caught Arrieta's no-hitter on April 21 in Cincinnati.
"We'll take a test drive and see what it looks like," Maddon said of Contreras' opportunity before the game. "He's definitely prepared for the moment."
It wasn't a good outing for Arrieta, who walked a career-high seven batters but pitched well enough to earn the win.
"It's not on Willson at all," Maddon said. "Jake was just having a hard time with the zone."
Arrieta gave up three hits over 5 2/3 innings to collect his 15th win, tied for the most in the NL with the Nationals' Stephen Strasburg. The seven walks were the most by a Cubs pitcher since Carlos Zambrano issued that many June 10, 2011, at Philadelphia.
"Willson and I are pretty comfortable with each other [despite] not having worked in an actual game together," Arrieta said. "He knows what I like to do, I know his catching style from behind the plate. That wasn't the issue -- it was just missed execution and not hitting spots in a couple key situations. That's what led to the five runs."
Contreras was promoted to the Cubs in mid-June, and the plan at the time was to have the rookie learn from Montero and Ross. Entering Thursday, Montero had caught 51 games, Ross 40 and Contreras 23. Montero has handled the transition well, said Maddon, who talked to the veteran on Wednesday.
"I mean this absolutely as sincerely as I possibly can -- I've been so impressed with him," Maddon said of Montero. "He's been a mentor to these guys. He understands what we're doing and why we're doing it. He's a positive force on the bench every day. Obviously, he's not happy with the season he's had on a personal level, but he's ecstatic with what we're doing."
Maddon said it would be easy for Montero to pout and become a distraction to the rest of the team.
"He's been the opposite," Maddon said. "He's in the right frame of mind. I give him all the credit in the world."
Maddon did not know Contreras well until this spring. The Cubs' plan was to get the young catcher involved with the veteran pitchers as quickly as possible.
"I could see he was very eager and definitely not afraid," Maddon said. "With respect to everybody he was going to catch, he was not going to be intimidated by them, and I love that."
Coach Mike Borzello has been a key in the development process, going over the game plan with Contreras.
"A catcher who is worth his weight in salt really is most worried about his pitcher and the outcome of the game and how his pitcher reacts and taking care of his guy," Maddon said. "That's your No. 1 priority. Sometimes when you're doing that, the hitting can suffer."

But Contreras has handled himself well at the plate, too, and is batting .266 with a .352 on-base percentage, seven home runs and 25 RBIs. Montero is batting .187 with five homers and 21 RBIs.