The decision has been made and golf's governing bodies have decided that using a putting method that anchors the putter to the body is not an appropriate way to putt. As I read article upon article about the reasons for banning the anchored method, I rarely see comments about the actual benefit of using a belly or broomstick method. Personal opinions and emotional reactions dominate the conversation. So utilizing the data I have accumulated over the past 8 years with my SAM PuttLab, I went back and took the time to research the differences of conventional and anchored method. Here is what I found.
The Anchored Method creates a more stable relationship of putterface angle to path shape and direction. In other words it is easier to keep the putter square to the path of the putter. The drawing below shows two lines. Black is the imaginary line to the target and the red the path produced utilizing a Putting Arc Training aide. I used this particular example because I consider it the average stroke path and for the sake of this discussion helps describe the impact of the anchored stroke. Please do not consider this an optimal stroke. The optimal stroke is the one produced by your posture and set up. It might have a smaller arc or bigger arc, and it will definitely have a directional bias. The arc tilts, but that is a discussion for another day. The important point is that almost all putting strokes travel on an arcing path. The true straight path is very rare. Less than 3% of our database.
In the next drawing I have added the putter position of the player who struggles with a conventional length putter. This is the common problem that forces unusual or extreme methods. The player attempts to keep the putter square to the artificial target line -black- rather than the true path created by posture and set up - red. To keep the putter square to the black line the player must manipulate the putter by twisting in a counter clockwise direction on the backswing ( closing )and then reversing the motion (opening) on the forward swing. Timing the rotation so the putter returns to square to the black line at impact.
The natural or non-manipulated action of the putter would be to remain in a constant position to the path of the putter. This is shown in the following illustration. Without manipulation or twisting the putter remains square to the path -red. Visually this looks like it opens and closes during the stroke. But the appearance is only because we reference the stroke to an artificial line not connected to the motion. By staying sqaure to the mechanically purs path it eliminates the timing requirement of the stroke. When the path matches the target line the putter is square to both. Reducing the need for perfect timing or over controlling the putter.
You can teach yourself this twisting motion with countless repetitions and by uses directional aides. In fact most drills and aides are built to hone the twisting motion. The problem is that under the pressure of competition, no matter how much you practice, structural mechanics will overcome so called muscle memory.
So for those who lose the timing of the twisting stroke, anchoring the putter becomes the solution. Anchoring the putter now forces the putter swing in sync with the rest of the body maintaining the relationship of putter to mechanics.
This is the only mechanical advantage of the anchored stroke, and once the player understands the advantage, he has a better understanding of the putting stroke in general. I think that is why we have seen a lack of concern in many of the players who use the anchored stroke. The change showed them the solution to their problems with a conventional stroke.