Our site has been affected too; we used to write 500 words articles and that used to work good earlier. But nowadays I don't think creating 500 words article will help your effort in search engine optimization. It will neither boost your traffic nor search engine ranking.
Nowadays social sharing of your content works great and Google also give high value to that kind of content. But it is not easy to create such content, because lots of factors are involved in this.
First and foremost you need to do lots of research so that you get yourself familiar with the topic what you are writing about. You need to maintain a transparency so you need to dig deep into the subject to give your readers a clear picture and make it interesting. That requires a great deal of time.
Provide as much information as you can.
All over make it a stellar one so that your visitors doesn't feel to urge to go somewhere else in search of same information