I think I read somewhere that anybody who hits over .200 BA should never sac bunt which eliminates almost everybody except most pitchers and Nefi Perez. Also The Book says you should ocassionally sac bunt just to keep the defense honest. If I am reading the chart right, a sac bunt increases your chances of scoring one run from 17.6% to 23%, but at the same time decreases your overall chances of scoring runs from 43.7% to 40.6%. Interesting to note that an opposing manager can decrease the chance one run scores from 23% to 16.1% by walking the hitter after the sac bunt, but that also increases the cahances runs score by 2%.