Did your partner add content that already appears on other sites? If so, the duplicate content filters may have kicked in. I have seen that affect more than just the pages with the duplicate content.
Google does not call it a penalty. They say that they only reduce the duplicate page's ability to rank well. That may be a technicality. I think that anything that reduces a page's ability to rank well smells like a penalty.
A lot of people so not take the duplicate content issue seriously, but I see it as a kiss of death for a web site, especially if the site is not very large.
"Democracy is two wolves and a lamb voting on what to have for lunch. Liberty is a well-armed lamb contesting the vote." -- Benjamin Franklin