In the February (Hot List) issue of Golf Digest, currently on the newsstands with the melting red driver on the cover, there's an article by Sean Foley discussing whether you should sweep your driver or think of hitting down with it. Of course, Foley teaches Tiger Woods and Justin Rose, among other top players.
Foley, surprisingly, says that if you frequently hit slices and pulls, you should NOT heed the common advice of sweeping your driver. He says that will likely only make your slice worse because you'll hang back on the downswing and make contact with your weight on your rear foot.
This is contrary to what I've always been taught and have read and heard for years. But when you think about it, Foley makes a lot of sense. Here's his reasoning:
"If you already have an open clubface and an out-to-in swing through impact--as most slicers do--hanging back will cause even bigger slices, as well as thin hits," he says. "To cure your slices and pulls, hit down on the ball with your driver. A good thought is to try to take a little divot after impact or to hit with the shaft leaning toward the target (left). This will help you shift to your front side on the downswing and swing into impact from inside the target line."
Foley doesn't mention how high to tee the ball, but I've noticed that Tiger, at least, usually tees it fairly low, and the equator of Foley's ball is just below the top of his driver, which is a little lower than what you commonly hear today.
Foley acknowledges that this thought of swinging down with the driver is counterintuitive. But he points out that two of the players he works with--Tiger and Hunter Mahan--almost always hit down with the driver, and they are not exactly short hitters.
Photo by Stephen Szurlej/Golf Digest