Maloney struck twice and O'Neill said: "Shaun kept going from where he left off scoring on Saturday against Fulham.
"His first goal was superb and his second wasn't bad and it set us on our way.
"Shaun is very hard on himself which is possibly a nice trait to have. I know what he's capable of doing and that was an example.
"I'm hoping he settles down because he's got that talent.
"I always worry about matches when we are expected to win. These games are always a potential banana skin and I didn't want to become another statistic."
Luke Moore, Marlon Harewood and Nigel Reo-Coker also scored as the Premier League side never looked liked suffering an upset.