CHICAGO -- The Cardinals made the choice following Monday's postponement to switch their starting pitching plans for the final game of this truncated series, swapping Luke Weaver and Michael Wacha in the rotation.
Weaver will now pitch on Wednesday at Wrigley Field, following Adam Wainwright. Wacha will start on Friday against the Reds on eight days' rest.
Manager Mike Matheny said the decision was strategic.
"We wanted to split up similar pitchers in Waino and Wacha, who are both high, over-the-top right-handers with breaking balls," Matheny said. "We have somebody like Luke, whose slot is completely different. The stuff is completely different. You're always looking, what's that little edge? That could be one."
Matheny also said that the club took into account Wacha's career struggles at Wrigley Field. Wacha is 1-4 with a 5.98 ERA in eight career games (seven starts) in Chicago. He went 0-2 with a 7.88 ERA at Wrigley in 2017.
"We don't deny that this has been a tough place for Michael to pitch in the past," Matheny said. "We had opportunities to split guys up, give them plenty of rest. We like how we split a couple guys up with similar stuff."
In explaining the decision, Matheny referenced his playing days as a catcher for the Brewers. Milwaukee's staff featured Ben McDonald and Cal Eldred from 1996-97. Matheny said the second starter in that alignment suffered when they threw on back-to-back days.
The differences between Wainwright, Wacha and Weaver are apparent in their build alone. Wainwright and Wacha are 6-foot-7 and 6-foot-6, respectively, and at least 215 pounds. Weaver is listed at 6-foot-2 and 170 pounds, and throws from a three-quarter arm angle.

Gyorko returns, but doesn't start
Jedd Gyorko is back after spending two weeks on the disabled list with a strained right hamstring, but not in Tuesday's lineup. Matheny instead played a hot hand and inserted Greg Garcia at third, with Matt Carpenter sliding over to second in place of the slumping Kolten Wong.
Gyorko's return complicates an infield alignment that Matheny planned to shuffle regularly coming out of Spring Training, but with one fewer spot given the way Jose Martinez has grabbed onto the first-base job. The question coming out of camp was how Matheny would find enough at bats for Martinez, but he's been the Cardinals' best hitter so far, while Gyorko missed time and Wong and Carpenter slumped.
"We're trying to put pieces together to try to make it look right," Matheny said. "Greg Garcia will be a part of it today. Jedd Gyorko will be a part of it soon. And Kolten Wong is going to continue to be a part of it, but there are things to work on. When it's not clicking, you have to go back to the drawing board and figure something out and make the most of those opportunities."
Carpenter was given the majority of playing time at third base in Gyorko's absence, but he could be more suited at second going forward given his experience at the position and lingering shoulder issues.
"Matt is more comfortable at second base, there is no question about that. He's always said that," Matheny said. "He's also done a nice job over at third. He'll continue to get opportunities at both."
Asked where he expects to see the most playing time, Gyorko quipped, "I'm just fine without playing the outfield."
Gregerson to debut
Back from a hamstring strain that forced him to begin the season on the DL, reliever Luke Gregerson could make his debut with the Cardinals against the Cubs. If he does, it will be in his hometown.
Gregerson went to high school in central Illinois but was born and played college ball in the suburbs of Chicago. That's where much of his extended family -- big enough to include 25 first cousins -- still lives.
The righty said that his family often rented rooftops around Wrigley Field when he visited as a member of the Padres, with whom Gregerson spent his first five big league seasons. He doesn't expect many in attendance this week, with playing temperatures in the 30s.
"We all grew up really close," Gregerson said. "I told people early on, my family is so big and extensive, don't call me when I'm here. I'm not leaving 150 tickets. I can't give some to one person and not somebody else."