Ross Sep 14, 2020
It is a term to roughly describe the extension of the arms/club ‘away’ from the body*. Some of it has to do with the amount each elbow bends. The term has some merit based on geometry. The idea is … the longer the radius … the potential for more distance and the more consistent the result. A full extension (front arm straight) at impact, would will help maintain a consistent radius thus helping to create a more reliable swing. It is only one factor. If the body tilt changes, great extension does not matter… the club head goes into the ground, or hits the top of the ball… or other.
* In my experience, width is often used to describe the moment in the backswing, when the front arm is roughly parallel to the ground as a “checking” point or “sign” of a potentially good shot or more advanced player.