It did affect my site. Its possible that the backlinks you got from sites with duplicate content got thrown out and that affected your ranking.
Yeah, After new Google algorithm content is more important. Your website has some poor or duplicate content which result as decrease in ranking. by adding some fresh and quality content you can get it back Thanks
Check this guilde line from Google for you to produce quality website http://humanwebsite.com.my/blog/how...p-you-in-your-search-engine-optimization.html