Thanks guys. So that mean -13 bat can be either end loaded or balance depends on the design of the bat by the manufacturer, right?
Not typically. Most bats with a -10 drop or greater are balanced. Bats with a drop of less than -10 are ussually end loaded, this is not a clear-cut rule though. What is most important is how it feels when you swing it. Example, my DD's 33/23 Demarini CF3 Black swings lighter than her teammates 32/22 Easton Stealth Speed, however both would be considered balanced bats.