Dear Jeremy,
The best tip I've ever seen about starting the putter back is from Loren Roberts. He says he starts the putter back with his lead shoulder shoving the putter back, instead of moving the putter back with his hands or arms. When the shoulder shoves the arms and putter back as a unit, the putter will necessarily head back (at least initially for a short distance at least) dead straight back along the same line as the shoulder alignment (assuming the shoulderframe is moving in a parallel plane to the line of the putt and aim of the putter at address). With this technique, it is physically impossible to start the putter out across the line of the putt, and the putter will either go straight back or will tend a little to the inside.
You can try this by setting up facing a wall with the toe of the putter near but not touching the baseboard. Use the shoulder to shove the putter back with the shoulders square or parallel to the wall. The putter should move so that the toe does not get closer or farther from the baseboard as the backstroke progresses (and the putter should remain square to the wall to boot).
Another technique is to "unweight" the putter at address before starting the movement back from the ball. This is Jack Nicklaus' term. Basically, this means to get the putter up off the turf resting poised or suspended on the cushy grass. This avoids the necessity of starting the putter back with some extra initial effort sort of like that required to "strike a match." Keeping this extra "strike" effort out of the start also smooths out the motion.
Finally, I sometimes think of the bottom of the putter (the sole) as a curry comb and the grass of the green a horse's mane. When you comb the putter back thru the mane, you have to keep the comb headed straight or the comb will tangle and snag in the hair. So I imagine the bottom edge of the putter face as a curry comb and then move it straight back as if combing the green.
Cheers!
Geoff Mangum
Putting Theorist and Instructor
Geoff Mangum's PuttingZone
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