What's up with Levon Aronian's form?

What are your theories on why Levon Aronian has been in such bad form after having been known as the World No. 2 for so long? Levon's last place at Norway Chess has been making me think about this.

Background info: Back in 2014, Levon Aronian won the WIjk aan Zee tournament in January. After the Zurich Chess Classic, he reached his peak rating of 2830. Then he participated in the Candidates Tournament and lost his first round game to Vishy Anand. Since then, he's had forgettable tournament performances and has lost rating points in order to move at least 20 points below 2800. He was well known before for his resourcefullness, which it seems like he's lost.