Switching to a more-lofted driver (10 degrees) helped, but the biggest contributor to Tiger's improved accuracy this week was his state of mind or, to be more specific, his peace of mind. Woods is finally at the point where he's trusting his surgically-repaired left knee, and that has allowed him to swing the club on a better path into the ball. Because Woods was being timid with his left knee, his shoulders were see-sawing back and forth during his swing. His right shoulder would drop back and his left shoulder rock upward, forcing the club too far under plane. This caused him to leave a lot of tee shots off to the right.
At some point in the last few weeks he's gained total trust in his knee again, and that's allowed him to rotate this shoulders on a more level plane through impact. His chest is no longer pointing up to the sky at impact, it's facing down toward the ground. This is a good image for anybody favoring a left knee or hip, or someone who falls back at impact. Get your chest to point down toward the ground, and you'll make much better contact.