What effect is made by shortening a driver by 1.5"?

Shortening a driver by 1.5 inches impacts several aspects of the golf club's performance and the player's swing. When a driver is shortened, it generally leads to a flatter lie angle, which can affect how the club interacts with the ground at impact. A flatter lie angle may lead to the player having to adjust their stance and swing to maintain accuracy.

The reduction in length can also decrease the overall swing speed, which can result in lower distance. This can render a player less effective in achieving maximum yardage since shorter clubs often generate less clubhead speed. The mention of "down 9 points" indicates a potential drop in loft angle or swing state, thus affecting the shot height and trajectory.

Overall, shortening a driver influences the dynamics of the swing, clubhead speed, and trajectory, which directly affects the player's accuracy and ultimately their performance on the course.