Paul Lambert's men currently sit in the relegation zone following a torrid first half of the season and have accumulated just 19 points in their campaign.
"Just driving down the motorway, you see the big stadium alongside and to think they could be playing Championship football is just unthinkable," BBC Sport quotes Foster as saying.
"If you'd said that three or four years ago, you wouldn't have believed it. But times change."
In contrast, West Brom, who take on Villa this weekend, are currently placed in seventh in the Premier League table.