Villa, after a poor start, have won their past four games in all competitions.
But O'Neill believes they will struggle, telling OLBG: "Tough start for them.
"I actually covered their live game, against Brentford a number of weeks ago and they were rock bottom. Really, really poor. Very poor indeed.
"Even (Morgan) Rogers was struggling and he's a very, very fine footballer. A really good player. No question about that.
"They could hardly mount an attack. Even when they got the ball into the box, didn't look as if they could score a goal.
"They look frail at the back. So all the elements of a side in trouble.
"However, I've got great faith in the manager. I've been saying this for some time. He's an excellent manager. His record has proved that there in European football.
"And I think that all the things that have happened pre-season, the frustration of the sort of rules that are attached and not getting as many players in as they wanted, maybe even losing young (Jacob) Ramsey to Newcastle.
"All of those have some sort of an effect for a while and then when you don't immediately hit the ground running, people start to compare or contrast it to the previous season or the previous couple of seasons.
"I don’t doubt that they will get back on track. Do I think that they're the same force as last season? I'm not so sure about that."