do you mean articles where just 15% of the content are unique and the rest are either from the product manufacturer or other sites?
So what % of content in a page has to be unique? The answer to this will be crucial as Google seem to have made a big change here.Obviously, there will be articles where many of us will like to retain manufacturer's description, but add our own content (text and/or media) and functionality, if any, over and above it.It doesn't make sense if google is expecting people to completely remove the original manufacturer's description.
Did you remove the pages that were thin (I think you considered pages to be thin if they had 150 words or less) or you added noindex to those pages? How exactly did you remove them as I am hearing google isn't ignoring pages with noindex tag in computing the site level panda score.
Congragulations on your recovery. :) Sorry for forgetting to do that before.