phranque - 2:43 pm on Jul 12, 2013 (gmt 0)
if you're loading a widget for social bookmarking and it's "down" - that could affect page load speed.
page load speed is used as a ranking factor.
in addition to what i described above which could affect your analytics...
and both respondents in this thread suggested you look at your server access log files for additional clues...
what does WMT tell you about Top Queries and Top Pages and changes over time?
have you tried segmenting your traffic in GA to see if that reveals anything?
have you tried various searches using the site: operator to see if anything looks weird? (too many/few pages indexed vs what you expected? any filtered content? non-canonical urls indexed?)
how old is your blog?
have you analyzed your inbound link profile?