With stats becoming increasingly important to the viewing of baseball, the traditionalist view of batting average as the most important gauge of a hitter's worth is being pushed aside in favor of on-base percentage. On-base percentage measures how often a player gets on base, not including reaching on an error or a fielder's choice.
The seemingly glaring flaw in this statistic is that it is too case sensitive. A player's spot in the batting order, the type of hitter he is and the game situation all affect how important the statistic is. Batting average, however, always shows that a player reaches base safely with chance of advancing a runner.
For a leadoff hitter, on-base percentage is extremely important. The job of the leadoff man is to generate offense by reaching base. With the leadoff man, how he reaches base is a null point; if he reaches base is what's significant. Thus, batting average is relatively unimportant.
After the leadoff hitter, batting average plays a much larger role. With the three, four and five hitters -- the players who are supposed to drive in the most runs and hold the power in the offense -- on-base percentage can be very misleading. Barry Bonds may lead the league in on-base percentage, but with a man on second or third, the Giants would much rather have him swing and attempt to drive in a runner than draw an intentional walk and allow the defense to set up a double play.
Similarly, Jim Thome of the Philadelphia Phillies has a significantly higher on base percentage (ranked 10th in the league) than batting average (ranked 50th). Yet, it would be much more useful for Thome to have a higher batting average. He is a slow base runner and his ability is wasted when he is walked.
On-base percentage does not take the importance of the home run into account. A home run raises on-base percentage as much as a hit-by-pitch. With batting average, though, walks are not considered and each point in the average is noteworthy.
Looking closer, batting average with runners in scoring position truly shows how clutch a hitter is. For example, Alex Rodriguez is having a great season statistically, but his failings in important hitting situations have often let the Yankees down.
An argument for on-base percentage is that if a team has a high percentage, they will generate runs and see success. The more players on the bases, the better chance they have to score. Michael Lewis' "Moneyball" detailed that Billy Beane, the Oakland A's general manager, is such an avid believer in on-base percentage that he acquires players with the statistic as a top priority.
The A's recent success has contributed to the growing belief in on-base percentage. Once again, this can be misleading. Consider that the A's have not advanced past the first round of the playoffs in recent years, and this year did not even make the postseason
This year, nine out of the top 10 teams in on-base percentage in the National League were in the playoff hunt; these same nine teams were in the top 10 for batting average. In the American League, the one playoff-contending team in the top 10 for on-base percentage and not batting average is, not coincidentally, the Oakland A's.
Overall, on-base percentage errs in varying in importance too much from player to player. Judging a leadoff hitter and a slugger by on-base percentage is an unfair assessment. Batting average holds equal weight with each player; a testament to the fact that they are major league hitters, able to get on base by their own abilities rather than a pitcher's lack thereof.
