Foster can see the difference between the experienced Villa team of previous seasons and the crop of youngsters invested in by current boss Paul Lambert.
Villa dropped into the bottom three after last week's home defeat against Southampton and have collected only one point from their last five games.
Foster said: "If you look at where they have been in the past, they have not only been top dogs in the midlands but a very big team.
"Look back only four years ago or so, they had the likes of James Milner, Ashley Young and Gareth Barry, they were beating the top teams regularly and finishing in the top six season in, season out.
"It's a bit of a fall from grace. Times change. With the state of the economy, clubs have had to tighten up and you can notice it around Villa quite a lot to be honest.
"The chairman (Randy Lerner) has set out the way he wants to do things. He wants to blood a young team and to see them come all the way through.
"I'm sure in two, three, four years time, they'll all be fantastic players, doing great jobs in the Premier League. But for now, it's tough for them.
"The inexperience really does show. It's hard for them at the minute."
When asked about the possibility of Villa being relegated, Foster said: "It would be incredible.
"Just driving down the motorway, you see the big stadium alongside and to think they could be playing Championship football is just unthinkable.
"If you'd said that three or four years ago, you wouldn't have believed it. But times change."
Baggies boss Steve Clarke reiterated his stance that striker Peter Odemwingie and defender Jonas Olsson, both QPR targets, are not for sale.
He said: "I don't know how many times I have to say but we don't have to sell anyone."