I'd say probably the clickstream data is saying people aren't clicking through to your actions and this may be decreasing your ranking. I've never heard of Facebook like buttons or Facebook Connect changing your rankings. The only thing I can think of is user-based algorithms messing with the ranking of your site.
I've heard Google has changed its algorithm because it couldn't distinquish between positive and negative signals. Apparently a small company got to a top position for its keywords by being rude to customers who in turn gave negative signals/ dislikes/ reviews.
Google got caught out on this so I would say it is a consideration and an increasing part of the puzzle.