The majority of golf equipment manufacturers would insist that the only putters that sell well feature intricate sight lines. This is the current marketing sizzle. However, from an instructor’s point of view, this can be a deterrent on the road to better putting for many people. Why?
In putting, everyone perceives the designated target differently. For example, if you have trouble seeing straight lines and are attempting to use a linear strategy (line on ball, lines on putter, every putt is straight mentality), more problems than solutions may be created. If you have linear tendencies and use a line on the ball, that is often a sufficient aid.
Sight lines on putter do not always point in the same direction as a perpendicular line from the face. Take a 2X4 and set it on the ground. Take your putter and square the face to the end of the board. Look at your alignment aid. Is it pointed in the right direction? You would be shocked at how many are not, and it really does not matter if it truly is aligned correctly. How it looks to you is all that matters.
The loft of the putter has some influence on this visual as well. With the face on the 2 X 4, move the shaft toward the target and away, keeping the face in the same position relative to the board. Does the line appear to change directions? Some designs are better than others, but more often than not this adds to the visual confusion.
Finally, many of us cannot accurately align the lines on a putter with a target when looking at them from the side. Our perception is that we are accurately aimed, but this is often an illusion. The most common mistake is that we aim the line at the ball, rather than the target. If the line points at the ball, we convince ourselves that we have aimed correctly because the ball has become the target, rather than aiming the putter in the direction we wish the ball to travel. When we use putters with lines that frame the ball, the problem often becomes worse instead of better. Now we really do a good job of pointing the putter at the ball. We have found that eliminating the lines on a putter takes away the distraction and helps the player focus on the intended line rather than on the ball.
Every time you add a layer of information to your putting strategy, you create a condition that must be controlled. This gets complicated, but it suffices to say that more layers cause more confusion and make the condition harder to stabilize. The confusion caused is so great that you are never quite sure what stroke you are going to use when you stand over a putt. Elimination of an incorrect visual reference helps strip away some of these layers.