When he was working with Butch Harmon, Tiger Woods had a lethal combination of length and accuracy, and a nuanced control of his irons that allowed him to knock down pins. He won eight majors in six years, and in my opinion, if he had stayed with Butch, he would've already broken Jack Nicklaus's record of 18 majors.
Since he started working with Hank Haney in late 2002, Tiger has won six majors. He's won despite bogeying the last two holes, despite missing fairways, by hitting irons off the tee and with a more prosaic game. Though less convincing than his previous triumphs, those wins kept arguments that he had lost something from gaining traction. Too bad. Tiger's backswing is so bad—so out and around, when it used to be in and up; so laid off, where it used to be more down the line—that it is almost unrecoverable. During the Butch years (1997-2002) Woods averaged 68.67% in driving accuracy; from '03 to '09 his average was 59.44%.
Now, a long-whispered-about coaching change has arrived, and while everyone agrees he won't go back to Butch, he should seek out a Harmon—Billy Harmon (above). Billy has worked with Jay Haas for years, and by all accounts teaches fundamentals, not a method. A straight shooter who is wicked funny, Billy is well-known to Tiger and considers him a friend. They have something in common as well: Billy is a recovering alcoholic who has been sober for 17 years and knows what it's like to fish in the lake of despair. I have no doubt that he would help Tiger get back on track.