According to the message printed at the bottom of the stats page (and as confirmed by Jeff's answer to this question):
Only non community-wiki questions and answers are included in these totals
However, if I look at the stats of the weblogic tag (for example), it says I answered 2 questions in the last 30 days (and I don't even appear in the all time stats). But the following search user:70604 [weblogic]
shows that I answered 14 questions (and 13 in the Last 30 days at the time of writing this).
IMHO, there must be a bug somewhere.
I've checked for questions mentioning the same issue but I couldn't find something really describing this behavior as a bug (and the Bug(?): incorrect answer count question and answer don't apply in my case).