Chico, 24, is 0-5 with a 7.18 ERA. He pitched his best game on April 11 vs. Atlanta, going eight innings and giving up just five hits and one run, but still took the loss in a 3-0 defeat.
He did not last more than five innings in any of his last four starts, losing three of them. He started Saturday against Pittsburgh and left after 4 1/3 innings, giving up eight hits and four runs and receiving no decision.
Chico did not disagree with Acta's assessment.
"I'm fine with it," he said. "I've been pressing a little too much. It's not mechanics. I was overthrowing, just pressing. I was trying to throw five wins in one game to get to .500.
"You can look at it that way, as being demoted, but I'm not. I'm still here. I could have been sent down. It's a different role, a different idea. Just go out there and relax, feel my way with it."
Acta said he envisioned Chico being used in long relief, maybe pitching the sixth and/or seventh inning. With O'Connor moving into the starting rotation, Chico will be the only left-hander in the bullpen.
O'Connor is 1-0 with a 7.71 ERA in three relief appearances since being called up April 24 from Triple-A to replace veteran reliever Ray King.
O'Connor, 27, went 2-0 with a 1.96 ERA in four starts for Columbus, striking out 20 in 23 innings and walking only four.
"He pitched very well in Triple-A," Acta said. "I can't wait to see him. Out of the 'pen it's been a little different. He's a guy who relies a lot on his changeup. It takes time to get a rhythm for those pitches he has, that big breaking ball and that changeup."
O'Connor liked the idea of being a starting pitcher again. He was a reliever his first two years in organized baseball, but mostly started for the past four years, including going 3-8 with a 4.80 ERA with the Nationals in 2006.
"This is what I've done in the past," he said of joining the rotation. "Knowing when you're going to pitch makes it a little easier to prepare."
O'Connor figured he is a better pitcher than he was in 2006.
"My slider's gotten a little better," he said. "My changeup's gotten a little more consistent. You're continually learning. Even last year, I had a tough year [3-7, 3.07 ERA for Double-A Harrisburg following elbow surgery in November 2006], but I still improved as a pitcher."