It seems that there was a pretty big limitation that Google wasn’t able to technically overcome before the release of the algorithm. This limitation centered around social signals as a ranking factor. With the release of Hummingbird though, Google has the capability to better process social signals. Granted, this isn’t the only thing that Hummingbird does, but Eric’s article centers around this particular aspect of the algorithm.
To check out Eric’s article about the Hummingbird update and it’s correlation with Social signals, follow the link below:
http://searchengineland.com/what-everybody-missed-about-hummingbird1-176031