Granato says this tip will help you when you need to hit the ball over a tree and carry a hazard behind it. But I think most of you will use this tip to hit your wedges and short irons a bit farther to hard greens, because the ball stops quicker when it comes down from a higher trajectory.
Here, take a look at the video:
In case you don't understand what Granato's suggesting, he wants you to let the last finger or two of your lead hand hang off the butt end of the club's handle. That means you won't grip the club with the last two or three fingers of your lead hand. Rather, you'll grip with the thumb, index and middle fingers of your lead hand. The last finger or two will just curl up against the butt end of the handle.
The result of this grip change is that you'll effectively get the length of a longer iron when you swing, which means you can hit the ball farther and higher. And that's why Granato recommends limiting this technique to clubs that are 7-iron or shorter -- the longer the club, the harder it will be to control your swing.
As I said, I suspect most of you will find this technique is most helpful when you're hitting to a hard green and need a higher trajectory so the ball will land softer, but the shot is a bit longer than you can normally hit your wedge. Gripping any of your wedges this way could give you another ten to fifteen yards of distance without sacrificing the height of the shot... and that should make it easier to stop the shot quickly.
But make sure you practice this shot before taking it to the course. With fewer fingers gripping the club, it's going to take some getting used to.