Newgrounds Wiki: Batting Average
Batting Average is average score for an author's Flash submissions. Only users who have submitted at least three Flash movies/games have this statistic. Posts, Experience, Blams/Saves, or popularity do not factor into a user's batting average.
There is a list of top batting averages which takes into account all of an author's submissions. In addition, every author has a separate batting average which takes into account only his/her top three submissions; that average is listed next to the results of an author search.