It will be Aquino's second stint with Baltimore this season; he had a 14.21 ERA in six games during April, but manager Dave Trembley attributed his ineffectiveness to lack of steady work.
"He was the 12th pitcher on the club when he was here before. There was a 10-day period when he didn't pitch," Trembley said. "When he did get an opportunity to pitch, his command wasn't what it should have been. That was probably my fault because I didn't give him enough opportunities."
The 30-year-old Aquino went to Norfolk after being designated for assignment on April 29. While with the Tides, he went 2-2 with a 2.45 and nine saves.
"I'm really looking for a seventh-inning type guy. I need somebody that can throw strikes and keep it where it's at," Trembley said. "We're going to give Aquino a shot and see what he can do."
Aquino made no excuses for his poor performance during his initial stay in Baltimore this season, but fully expects to be better this time around.
"Honestly, I don't know what happened. I don't know what was going on to (mess up) my mechanics and my pitches," he said. "I felt bad when they sent me down, but what can I do? I can throw better than that. Let's see what happens now."
Aquino, who was claimed off waivers from Milwaukee in December, has pitched in 132 major league games in his career with the Orioles, Arizona Diamondbacks and Brewers.
Bukvich had a 6.75 ERA in four games since having his contract purchased by the Orioles on June 22. He issued six walks in 5 1/3 innings.
"I just don't think he threw enough strikes. I don't think you can afford that luxury of putting guys on without them hitting their way on," Trembley said. "I don't think there's any substitute for strike one and staying away from the base on balls, especially late in the game."