The reason for holding the sticks by their shafts is because they last longer ! - when a drummer is "riding" on his/her cymbals ,the cymbals cut into the wood , also when your playing your hands get sweaty and holding the sticks by the shaft is easier , hope that helps .
What is the anatomy of a drumstick exactly?
I can imagine there's a tip (or "head", possibly), and a shaft. What else is there? The wrapper it came in????