If I understand correctly, you had a lot of Web pages at a site with a set of URLs, and then you trashed those addresses completely and substituted new ones. That's like starting a new Web site almost. And about that time you noticed the problem - so that is probably the reason.

The degree to which 301 redirects are recognized and trusted by Google is unknown. They tell you that they do not list redirection pages at all, or at least they used to do so. That is obviously untrue. But they seem to give a lot less weight to such pages. Never change a URL if you can help it.

Even if there is no penalty whatever for redirection, the indexable content is now at a different Web page. The old page has nothing in it, so whatever google moxie you had there must be gone, right? The new page has to start over.

It seems that every two weeks or so there is a post from some poor soul that starts "We changed the domain name of our site" or "we changed all the page addresses" and "for some strange reason we aren't getting any more visitors."

Do you think there just might be a connection? I rather suspect there is.

SEO - Search Engine Optimization