Degrees of freedom describe the flexibility of motion. It is used in the sciences to describe the number of directions an object can pivot or move.
Our human anatomy allows us to move our joints in multiple directions. This attribute of suppleness works well when we can control our movements, and not so well when we lose control.
Frank Thomas, the past Technical Director of the United States Golf Association for many years, used the term 'degrees of freedom' when he referred to the various movements that are possible in the putting stroke.
"The more joints that can easily bend or twist during the putting motion, the more degrees of freedom a player has when putting, which gives more flexibility and feel, but can result in more inconsistent putts".
He was comparing the unfair advantages of the belly and long putters over the standard putter. These non-conventional putters are able to eliminate certain degrees of freedom, and the errors associated with them. This is because you can anchor the butt of your putter to your body.
The USGA overruled his recommendation that the belly and long putters be banned from the game and they are now commonplace on putting greens around the world.
The setup at address is static in the sense that you determine through habit certain positions. For example, you decide whether to arch your wrists and whether to tuck your elbows into your side. You decide the degree of tilt at your hips and the amount of flex in your knees and so on.
It is the upper body that is primarily responsible for the dynamic act of putting. It consists of joints that can move in different directions. This is both helpful and harmful to a consistent pass at the ball with your putter.
The potential for error arises when you fail to eliminate, or at least control, the degrees of freedom associated with your putting stroke.
Degree of Freedom - Raising your putter vertically up and down off the ground.
The recommended setup at address is to allow your arms to hang heavy and free of tension. There is a degree of bend at the elbow joints, but this is cause by the normal muscle attachment of the upper arms to the lower arms.
If you use a putter that is too long for you, you will be forced to increase the bend in your elbows in order to position your eyes over the ball. This is a 'held' position because it requires a certain muscular tension to maintain this angle.
Degree of Freedom - Breaking or cupping your wrists during the putting stroke.
The recommended method of putting now is to remove the wrists from your putting stroke. In other words, you should putt with 'dead hands'. The exception is a long putt where you need a certain amount of wrist break.
Overactive wrists are the primary reason why some golfers have changed to the belly and long putter. The anchoring of the butt end of the putter has taken the wrists out of play, thereby eliminating one of the degrees of freedom.
Degree of Freedom - Allowing your wrists to rotate open or shut during the putting stroke.
In both the vertical and tilted putting stroke the path of the putter head should remain square to the arc of the swing. If you allow the putter head to fan open on the backstroke or to fan closed on the forward stroke, you are changing the angle of your putterface.
Errors in the angle of the putterface to the aimline are a greater cause of missed putts than a putter path that cuts across the aimline.
Degree of Freedom - Moving the putter head towards or away from the body.
Grounding your putter behind the ball fixes it momentarily in a certain position relative to your body. It is often recommended that you hover your putter at address so that it can find its natural hanging position before adopting your stance.
This will avoid any tendency for your putter to fall towards you or move away from you during the start of your backstroke.
Degree of Freedom - Moving the hands forward at the start of the backstroke.
When we address the ball, it is customary to have the hands level with the putter head or slightly forward of it. In other words the putter shaft is either vertical or it leans forward a fraction. However, some golfers change this setup position when they begin their backstroke.
In order to initiate a smooth take-away, they employ a trigger movement. This is often a forward press just before the start of the stroke. There is nothing wrong with this so long as the loft on the putter is not compromised unduly.
Degree of Freedom - Rotating your shoulders left and right during the putting stroke.
Whatever your preferred putter path is, your putting triangle of shoulders, arms, wrists, and hands must move as one unit in order to keep your putter on plane.
Rotating your shoulders during your stroke is not a fault. However, allowing your forearms to rotate independently of your shoulders destroys the integrity of your putting triangle. This will lead to greater inconsistency in your ability to square your putterface at impact.
You need flexibility and movement for feel, and too much constraint is as bad as too much movement. However, the more precise and compact your setup and putting stroke is, the more you will be able to control the various degrees of freedom that can lead to putting errors.