"It's nothing. In the scheme of things it's really unimportant," he said of Barry's selection as skipper.
"I'm more disappointed about losing the game so the captaincy is not the thing. I was more than pleased to give it to Gareth and he was more than pleased to get it.
"Martin Laursen is captain of this side and he missed out tonight, Nigel Reo-Coker has led the side in the past and he wasn't in the starting line-up.
"That left Gareth as the obvious choice, and why not?"
Barry, booed by a small section of fans earlier this year, received a warm, if not deafening, ovation from the Villa faithful when he was announced as captain but O'Neill played down any symbolic aspect to his decision.
"He didn't hold a speech or anything like that over it but he was, I'm sure, pretty pleased. He doesn't give much away but I think he was pretty pleased - as anyone who gets the captaincy at this football club should be."