"I'm aware of what he is capable of but it is something the Villa fans have seen all too seldom," said O'Neill of the 28-year-old midfielder. "Bolton was a big, big day for Stiliyan and he got a great reception because he played very well.
"I'm pleased for him because he can play like that and he was excellent."
He added: "I think he was up for the game, which was obvious from his performance, and by half-time his confidence was really high.
"I thought last week at Old Trafford there were signs when he didn't do too badly in the game. I was pleased for him because the last time he played at Villa Park, I took him off in the game at half-time against Newcastle.
"He is capable of producing and that is why I signed him."