Understanding the kinetic link principle should immediately reveal the differences between good and poor exercise selection for rotational power development. First, as the old adage states, it's all in the hips. A strong foundation is where it all starts. No need for sport specificity here, jumps, hops, bounds, O-lifts, deadlifts, and squats will do. As I mentioned previously in the series, a strong athlete is worthless if he or she can't move effectively. Isolated joint stability and mobility must be addressed as you build strength and power. Specifically, hip mobility will allow optimal extension through the back leg, rotation and flexion into the lead leg, while allowing the torso to remain stable in order to transmit force to the arms.
The most common error in training for rotational sports is the implementation of exercises that promote motion through the lumbar area, instead of restricting it. This area must be built for stability, not mobility, as evidenced by EMG work referenced in Part 2 (and not to mention every piece of McGill's research regarding spine health). This eliminates every exercise that sounds like a medieval torture device or poisonous creature inlcuding: russian twists, jack knifes, iron crosses, prone scorpions, and cobras. Bridging, physioball bridging, chops, lifts, cable core press, and the Extreme Core Trainer (landmine) are 6 of probably 1,389,547,273 exercise categories for "core stability". Use them, a lot.
Finally, and most specific to the development of rotational power, is actually teaching rotary mechanics. Medicine balls are a strength coach's best friend when it comes to teaching the mechanics of rotation. I outlined a progression for med ball work in an article entitled Elastic Core Development with Medicine Balls, located on www.strengthcoach.com and www.sbcoachescollege.com, one of the best free S&C websites on the internet.