The decision was two-fold. It gets Reed Johnson a chance to start his first game, while giving the left-handed hitting Yelich a breather against southpaws.
In the first five games, the Marlins have faced four lefties. On Friday night, the Padres went with southpaw Eric Stults.
"We've run up against a bunch of lefties," Redmond said. "This is a chance to get Reed in there, and give him a chance to get some at-bats."
Yelich, 22, is a promising young hitter, who has been leading off because Rafael Furcal (left hamstring) is on the disabled list.
Yelich is 1-for-10 against lefties this year, and 3-for-19 (.158) overall. On Thursday afternoon, he stepped up with the game-tying RBI single in the eighth inning in Miami's 8-5 win over the Rockies.
"I feel comfortable," Yelich said. "I've had some good at-bats. The results haven't been there. Obviously, it's only been four games."
On Saturday night, Yelich is expected to return to the leadoff spot against hard-throwing right-hander Andrew Cashner.
"I think his approach has been fine," Redmond said. "Maybe the one disadvantage for him is we didn't face hardly any lefties in Spring Training. Then to come right out of the chute and face four or five in a row, that's hard. Obviously, he hasn't had a whole lot of success up to the point against lefties.
"But I still feel great with him up at the plate. Yesterday, he didn't kill that ball, but he ended up getting a big hit. I still feel great about him in that leadoff spot. I feel he's going to make the adjustment. It's just going to take a little time. He's got to stay with it."