Originally Posted by pbryd
This is what I'm hoping I did wrong. If it is, then the site might climb back up before too long.
I put an html redirect on the old html pages to the new WP ones, then I got worried about it being hit for duplicate content, so I just deleted all the old html ones.
I may have been a bit foolish
A 301 redirect is to tell Google your page has moved and thus prevent
duplicate content issues, not create them.
In your .htaccess add:
redirect 301 youroldpage.html yournewpage