The right-hander, who had trouble throwing his fastball for strikes, allowed seven hits and had three walks in 1 2/3 innings of a 16-2 loss to the New York Mets. He threw 71 pitches.
"I pitched great the last few times out," Wainwright told reporters after the game. "Today, the ball was going a little more horizontal. There was good run on the ball, but it wasn't sinking like I wanted it to. It's probably a hand-placement thing. I haven't watched the film to know.
"My body feels great. My pitches are there. A lot of foul balls today, a lot of pitches in the middle of the plate. And I usually don't do too much of those. ... This is what spring training is for. Obviously, you don't want to go out there and give up 10 runs. But that's what we're here for."
Cardinals manager Mike Matheny chalked up the outing to just "one of them days."
Wainwright, 35, has two starts remaining this spring. And despite his 10.97 ERA, he doesn't seem worried heading into the regular season.
"I'm very confident," Wainwright said. "It's hard to look you in the eyes and say that after a 10-run game, but I'm very confident that things will be good."