Dear Michael,
Pros typically sink putts averaging about 4.6 feet. I think that means that the average length of all putts that find the hole is about 4.6 feet. Loren Roberts has the lengthiest first-putt distance on tour of about 10.5 feet.
To avoid closing the face, try thinking of the leading edge of a putter as a comb stroking thru long hair: if the comb twists out of straight, it will snag.
Also, since you will either be stroking up thru the ball or stroking level thru the ball, you can aim to move the sweetspot of the putter face thru the front of the ball that is nearest the target. The sweetspot will then move thru the back dimple on the equator and out the front dimple that is nearest the target, so it won't "pull" left. If the putter is traveling upward thru the ball, think about lifting the sweetspot out the front. If stroking level, just ignore the back of the ball and move the sweetspot square out the front of the ball.
Another tip is to avoid letting the left elbow go toward the left hip (right-handers). To avoid this, with a shoulder stroke, the left shoulder has to start rising vertically awayt from the balls of the lead foot right when the stroke bottoms out in the middle of the body before impact with the ball (played about 2 inches forward of the middle / bottom). This shoulder lifting effectively "lags" the left elbow and hand upward along behind it, and this trajectory effectively sends the elbow down the line of the two feet, parallel left of the putt line. In other words, this action avoids a pull.
If the face is closing simply because your left or right hand is active in some sort of gating pattern, then think about moving the back of the left hand straight along the line of your feet parallel to the putt line. Just don't allow the hands to rotate any.
Let me know if this helps.
Cheers!
Geoff Mangum
Putting Theorist and Instructor
The PuttingZone.com
http://puttingzone.com
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