There’s an age-old controversy that many golfer’s have yet to resolve.
Should the putter head be swung straight-back straight-through or should it swung on an arc?
The answer is simple: it’s both. How could it be both you ask? Well it has to do with what part of the putter you are focused on. It’s the shaft that moves straight-back straight-through, while the sweet spot of the putter head moves on an arc!
For a putter with an approximate 70 degree lie angle, the shaft moves on an inclined plane. It’s (1) the incline of the plane, and (2) the relatively smaller movement of the butt end of the grip, that causes the putter head to move up and in as the putter head is swing back. It’s the up and in that creates the putter head’s arc.
In order for the putter head to move straight-back and straight-through, it’s the shaft that has to move an an arc! And it’s not easy to produce the necessary shaft arcing required to keep the putter face square to the target line.
Watch the following video for a more in-depth discussion: