"He's still got to improve but Martin has made a decision, which you have to accept, and he's brought in Zat Knight and Curtis Davies," said Bruce.
"It was his call. Martin's obviously looking to get a team into that European place, that's his remit. It's all about opinions. I think I got a terrific bargain in Liam. He had no qualms about coming across the city.
"When you look at his statistics, he's a boy of 23, he's played nearly 100 times for Villa. For us it was a no-brainer."
O'Neill admits he is not surprised to see Ridgewell captaining Birmingham, despite letting him go.
"He's doing fine, they're pleased with him. He wanted to go and that happens," he said.