Again, at SMX West last week, Paul Haahr from Google said that when Google launched their knowledge graph in 2012, they decided to put entities at the forefront of their query analysis.
He explained that in order to show knowledge panels, the query needs to understand if there is any entity data there. So they moved that to the first part of the query analysis back in 2012, in order to surface knowledge graph data.
Here are some tweets with the information:
Forum discussion at Twitter.