I'm not saying it was some uber-leftwing party. I'm saying that if you read the Democratic Party Platform, it's marginally to the left of what Clinton campaigned on, economically (e.g. note the section on mergers and monopolies, absent from the current platform). There's very little ground between the Democratic Party now and then (in either direction).
The Democratic platform isn't more to the left, it's that the Democratic party is more internally consistent - Democrats vote more like other Democrats than they used to (or: the 'mean' Democratic opinion is unchanged, but the 'standard deviation' of Democratic opinion has reduced).