Phil shortened his driver swing a few years ago, and won his first major because of this and other conservative measures. He went back to his longer swing afterwards, feeling he would do better with longer tee-shots. A questionable strategy, but Phils will be Phils (and perhaps pros are under some pressure (or have some incentive) from their club sponsors to hit it long?). Of course he made the more aggressive strategy work for him at the 2006 Masters, but he required 2 drivers to execute it!