CHICAGO -- A meeting Sunday of St. Louis Cardinals manager Oliver Marmol, pitchers Adam Wainwright and Jack Flaherty, and catcher Willson Contreras led Marmol to declare the day "one of the most productive" of the season.

It came amid confusion over why the Cardinals switched Contreras from being their everyday catcher to serving as their regular designated hitter after signing him to a five-year, $87.5 million deal this past winter.

But Marmol didn't provide much clarity on the subject before Monday's 3-1 win over the Chicago Cubs.

"There's so many different layers and elements to what we're talking about," Marmol said. "We are making sure he understands the full process of how we think through a game plan."

Marmol was asked to be more specific.

"That's the part I unfortunately won't disclose and that's the part that won't make sense to the rest of the world," he said. "It just won't. I'll wear it until then. That's the part that will stay in-house, and at the end of the day, it won't make sense to anyone else, but we do feel confident in the end product."

Cardinals pitchers are 10th in ERA (4.59) in the National League but aren't blaming Contreras, despite his benching. The meeting Sunday was to tell him just that -- and how much they need and appreciate him.

"I do want to share something because I don't want this to get over-compounded in the media without everyone knowing all the information," Wainwright said. "What we did was we sat him down [Sunday] and just poured into him: We love this guy. We're glad he's here. We want him to be our guy.

"Honestly, I don't know if anyone's ever told him that. But he's appreciated. We love him. And we're glad he's here. We're glad he's part of our team, and I think it's going to be a huge force for us going forward."

Contreras is returning this week to Wrigley Field for the first time after playing his first seven seasons (including the 2016 championship campaign) with the Cubs. Before addressing his situation with his current team, he expressed nervousness about how Cubs fans would treat him.

While the Cubs honored Contreras with a video presentation before the game, when his spot as the cleanup hitter in the St. Louis lineup was up to begin the second inning, the mixed response he had predicted erupted in full force.

"It was what I expected," a beaming Contreras said after the game. "There was a lot of love. I got a lot of booing. It was fun to be back at Wrigley Field and playing, and I enjoyed every second."

After the din died down, Contreras rapped a 103 mph single up the middle off former teammate Marcus Stroman. As the booing portion of the crowd weighed in again, Contreras surprised even himself with a "bring it on" waving gesture.

"I found myself doing it; I was like, 'OK,'" Contreras said. "It was fun. I think the team needed that. What I liked the most was that my team was there for me."

After the boos died down, Contreras came around to score the game's first run on Dylan Carlson's single. Contreras then grounded out in his second at-bat, notable because his exit velocity was one of the highest of his career: 117.5 mph.

In the sixth, Contreras hammered a Stroman curveball 108 mph off the ivy in center field for a go-ahead, RBI double. When he reached second base, the "bring it on" gesture was back.

Contreras drove in the game's last run on a fielder's choice in the eighth, finishing with two RBIs and a run scored.

As for being removed as the Cardinals' catcher, Contreras said pregame he believes he'll have a short-lived stay at designated hitter.

"I can't wait to get behind the plate," he said. "That's what my passion is about. That's what the Cardinals got, a passionate guy that likes to work, likes to get better and likes to be behind the plate. And they know that, so right now, just focused on getting better, back on the field and especially behind the plate."

The Cardinals are mired in last place in the NL Central, nine games behind the first-place Pittsburgh Pirates. Pitching has been their biggest problem as the team attempts to move on from potential Hall of Fame catcher Yadier Molina.

"Yadi's presence here has been documented but also hard to replace," Wainwright said pregame. "But it certainly doesn't speak to being 14 games under .500. Don't get me wrong, Yadi's the greatest catcher [who] ever lived, in my opinion. But does he make us go from 10 over to 14 under? That's on us."

And apparently on Contreras, though the team is attempting to turn that narrative around. The Cardinals believe the short-term pain of the current situation will pay long-term dividends.

"This is not going to feel good," Marmol said. "The timing [of Contreras' return to Wrigley] sucks. But it's a small blip in the story over the next five years. ... This looks reactive -- it'll sound like s--- when I say it -- but I actually think it's proactive."

ESPN's Bradford Doolittle contributed to this report.