Question: does a sac fly count against your batting average

Answer: No, The purpose of not counting a sacrifice fly as an at-bat is to avoid penalizing hitters for a successful action. The sacrifice fly is one of two instances in baseball where a batter is not charged with a time at bat after putting a ball in play; the other is the sacrifice hit (also known as a sacrifice bunt). But, while a sacrifice fly doesn't affect a player's batting average, it counts as a plate appearance, thus lowering his on-base percentage, and a player on a hitting streak will have the hit streak end if he has no official at-bats but has a sacrifice fly.