When the club is releasing it is like a pendulum, the club is swinging about a point at the wrists. While we cannot shorten the length of the club shaft during the swing we can apply more centripetal acceleration than is needed to keep the club rotating. We can tug "UP" at just the right time thereby injecting kinetic energy to the club head. When done in the final stage of the downswing this is effectively the same thing as "reducing the hand path radius".
All long hitters do it. They may not know they're doing it ... but all long hitters inject that final dose of energy by "pulling up" at the end of the downswing. Some even end up on their toes as a result like Bubba.
Its all in the hands folks... use your body to make your hands go where they've got to go.
This is reminiscent of Wild Bill Mehlhorn, three-time PGA TOUR leading money winner in the 1930s and the man Hogan called "the greatest ball striker I ever saw". http://www.golfwithmehlhorn.com/book.htm [If you order anything -- Book, DVDs, Swing Aids -- ask for the LBG Member discount].
Bill felt like he was "hitting up", even when he took a divot. On his long shots, he tried a right hand uppper cut to the chin. In his own words, he tried to "knock myself out".
With his big pivot and the principal 'clubhead swinging' feels the thumb and forefinger of both hands (all other fingers much lighter and even letting go), his Golfer's Flail (Sketch 2-K) really worked.