We all know that a home run is better than a base hit. A double and triple are better than a base hit, too. And players who can hit for extra bases or hit balls out of the park consistently are generally thought to be better and more valuable players than singles hitters. But how much more valuable are they?
The stat "slugging percentage" is supposed to help quantify not only a player's batting average, but how often they hit extra base hits. You calculate slugging percentage by adding (1B + 2x2B + 3x3B + 4xHR) and dividing by total at-bats. So extra base hits help inflate a player's slugging percentage more than just hitting singles.
For example, Kelly Kretschman of the USSSA Pride currently has a .489 batting average but a .804 slugging percentage because she hits a fair amount of extra base hits and home runs. Seventeen of her 45 hits this season have been doubles or better.
Her teammate Hallie WIlson has a .324 batting average and only a .380 slugging percentage, because only 5 of her 35 hits have been doubles or better.
Sabremetricians have long touted slugging percentage as a better way to measure the value of a player than batting average, because batting average does not take into account a player's power numbers. Should we ditch batting average and switch to slugging percentage?
I expect that slugging percentage will have a much higher correlation to win percentage than mere batting average. Teams with the highest power numbers should win more games, right?
To test this theory, I compared the batting averages and slugging percentages of the top 100 of NCAA teams to their win percentage. Correlations are measured on a scale of 0 to 1; 0 means no correlation and 1 means a perfect correlation. What I found when I measured these numbers surprised me:
I expected a much higher correlation between slugging percentage and win percentage, but the truth is it was barely higher than the correlation between batting average and win percentage. The correlation is 0.525 for batting average and 0.612 for slugging percentage. The difference is only .087 of a percentage point, or a 16% difference.
The data indicates that, while power is a little more important than just getting a hit, it is not as important as you might think. The ability to make solid contact and find gaps in the defense is what is really important, not how many bases the hit results in.
So batting average still has a prominent place among the stats we use to judge our best hitters. It is not time to abandon batting average for slugging percentage quite yet.
And for all you young hitters out there, stop swinging for the fences! Look at the data and discover that getting the ball in play is what counts—finding a place for it to drop on the field is basically as important as hitting the ball hard!