Arched wrists position the putter shaft so that
it is better aligned with your forearms.
Arching your wrists in your setup puts them in a good alignment. By matching your hands and wrists to the angle of your forearms and putter shaft you promote a one-piece putting action.
The way to arch your wrist is to point your thumbs down the line of your forearms as if you were casting a fishing rod.
This helps to remove from your putting stroke unwanted wrist action in the form of hinging up and down.
Horton Smith, first winner of the US Masters and lights-out putter, stated that the downward curve of your wrists is a fundamental step of a good putting stroke.
This is because it promotes keeping the putterface square to the line throughout the stroke and minimizes the tendency for the putterface to fan open to closed.
Whether you putt with arched wrists or not is a personal choice based on the putter path you prefer to use. Bear in mind that the lower your hands, the more your putterface will rotate in your putting stroke.
Bernhard Langer in his book Langer on Putting observes that the higher your hands at address the more naturally the putter head will move back and through in a straight line. The lower your hands at address, the more curved an arc you are likely to produce.
It is important, irrespective of your putter path, that you sole your putter on the ground. If your hands are too low, the toe of your putter will be higher than the heel. If your hands are too high, the heel of your putter will be higher than the toe.
Steve Stricker, one of the most consistent putters on tour, sets his wrists with his forearms in line with his putter shaft.
Travis Fulton, Director of Instruction at the PGA Tour Academy observes that:
"Stricker sets his left wrist level to slightly un-cocked at address. The condition of the left wrist allows the putter to sit more in the palm versus the fingers and allows the left forearm to be in-line with the putter shaft."
If you are using a pendulum-like stroke you want your putting triangle of shoulders, arms, wrists, and hands to move in unison with your putter. The more your forearms are aligned in the same plane as your putter shaft, the easier it will be for you to control your putter.
The alignment of putter shaft and forearms demonstrated by Stan Utley is a good example to follow.
Matching your hands and wrists to the direction of your putter shaft promotes a one-piece putting action.
If your putter shaft and your forearms are too far out of line so that you can see from a side-on view the butt-end of the putter grip, you introduce another dimension or potential for error.
This is not a good setup position.
1 = Illustration Horton Smith 'The Secret of Holing Putts'
2 = Illustration Bernhard Langer 'Langer on Putting'
3 = www.golfdigest.com
4 = Illustration Stan Utley 'The Art of Putting'