Commentators were talking how Dhoni (#1 ODI player atm right?) uses leverage, shifts weight down dropping center of mass by "going under the ball" and shooting his hips up to generate power and hit six. Same biomechanical application is also used to muay thai for rotation of your upper body with arms and hip as one piece (by favorite analogy are the aciton figures) and generating more power. Again note the similarity of mechanics in golf swing and how it can be applied to cricket shots if used wisely with ease.