O'Neill apologised for the timing of his departure five days before the start of the 2010-11 campaign after his side fought out a goalless draw with Villa.
But he is adamant he left Villa in a stronger position than when he took over in 2006.
When asked about the fans' reaction, O'Neill said: "I think it's a very natural reaction considering I've been gone two years and they've never known my reasons for leaving.
"It is very natural, I was expecting it and I got it.
"With the idea that I left them in the lurch, I apologise maybe for leaving five days before the start of the season.
"But I came to this football club a fortnight before the season started with a team that had almost been relegated the previous year.
"The timing was not great five or six days before the start of the season but I think the team I left behind was infinitely better than the team I had started with.
"Listen, in the scheme of things it's a sideshow today and the main event is the two teams. It will always be that."